A little work with a razor saw could remove the heads cleanly enough to reuse without any problems. I've had pretty fair luck just scoring a line with a saw or the back of a #11 blade along the glue joints then flowing some liquid cement along the lines and letting them soak for awhile, usually then they can often be removed at the original glue joints. A little bit of information for the next time.
What I thought looked modelish (a new word for the dictionary?) Was the front header above the headlights had a different curve to it it kinda flattened out then took a curve up to the hood. But those tires almost changed my mind, the most realistic aged rubber tires I've seen on ANY type of model.
I've got four of the two different original releases, and all four of them have the same sink marks you've described, plus the bottom side of the upper trim molding hasn't got any definition at all, after spending a full day of playing with it on one of the bodies I decided to wait until I was really feeling adventurous and relaxed.
It looks like it would be a pretty straight forward deal, doing it with styrene would make it a lot easier than metal, trimming the bottom of the cab and back part of the front fenders would be simple, and taking a template on tape, then applying the tape back to the front clip to use as a trim line. A lot of the fender work could probably be accomplished with a sanding stick. The design of the cab should make it easy to just move the interior floor straight up and trimming off the extra length of the firewall and door panels (if using them) to fit. This will be a really cool looking truck when it's done, I like all the work you did on the frame, if you can do that, the body mods you canprobably do in your sleep.
It must be one of those photo vs. actual car deals, but it appears that the truck in the first photo has been sectioned around 8 -10" just a distortion from the angle? Look closely, you should see what I mean, and it gives the truck a serious attitude, looking at the pictures again it appears that the section job was done along just the lower edges, and is just about the amount of material from the bottom of the grille down. There was a lot of cars done this way back when. The only real work done was to apparently remove the material on the front part of the fenders from just above the curve at the front of the wheel opening, and then molding that part back to the fenders.
I think you can get one of the Tremec TKO six speeds from one of the newer Viper kits if you're interested, and correct me if I'm wrong, but didn't they use another set of rear fenders and swap sides with them for the inner fenders in the bed? Could be that I'm confusing that feature with the Orange Chevy truck they did clean up work on, the older I get the more of these ideas seem to get thrown together and my memory of what file they come from gets confused.
One thing I noticed, and it might just be distortion from camera angle, but on the 1:1 the beltline molding on the quarter panels matched the beltline on the rear of the cab. This is one of the details that I was really impressed by with the original build. I think you're doing a great job, a couple of details on the frame are just a little different but aren't worth doing something to them unless you're really going for exact, and those are the running board brackets on the original don't have the bulky vertical piece that goes vertically up the side of the frame rail. This one should really be ahead turner when you set it down on the table, I plan on watching this one very closely.
There are actually a lot of Bonneville records that were set on a circular course, Mickey Thompson set a few in a couple of Mustangs, and Buddy Baker and the K&K Dodge Charger from NASCAR set some, there are still a few that are FIA endurance records for time and distance that still stand, but I doubt if the salt will allow room for a five mile circle track to be set up again.
Extremely clean build, especially like the attention to detail, like the way of mounting the Lynx air cleaners so they flowed like a continuous element instead of just two air cleaners stuck on top of the carbs. Only thing I think I might have done differently was to turn the striping on the rear panel over to make the width of the rear window flow into the striping a little smoother.
Our fickle nature is praising the abilities of Moebius to do what some think is the undo able for U.S. manufacturers to do, while over in the truck section they're being crucified for the two long awaited Ford pickup truck kits. Me, I'm just going to get a short bed one to build a street rod out of and if I like it I'll do a copy of the most useless and undriveable piece of junk any truck manuscript ever pawned off to the public, the '71 -'72 Ford Ranger Camper Special XLT with the 360 boat anchor for power. My dad bought a new one in '72 and the motor broke a rod with less than 600 miles on it, and afterin it died on him for the umpteenth time crossing a four lane highway in traffic he traded it in on a new Chevrolet 4wd stepside that went 300,000 miles without any problems other than changing one set of plugs at 60k miles.