All of the info. given here is all good but the bottom line is whatever changes you make to the body that makes you happy.
This is simply my opinion but I don't ever get worked up too much with actual 1:1 measurements as a guideline. A lot of eyeball engineering and trial and error to get the desired results.
Here are a few shots of bodies that I have created and you should be able to see where most of the cuts and added styrene has been added. It will give you a basic idea of how much work may be involved in achieving what you are looking for.
Now, even though I don't think that actual measurements are all that critical reference material is invaluable. Most of what I created came by way of using every bit of real car ref. material as possible. For example, in the case of the 69 Daytona I used every bit of research available from Vanishing Point race cars website when it was up and running. That was over 100 detailed photos of how the real car was done.
I hope this helps in some way.
That is another good way to do it. Those 1:1 measurements are not a must have for an experienced modeler that has done these things before too, but they help a lot when doing these first time I guess. I planned, that I will be doing so that I start cutting and building it to match those 1:1 measurements and then see how it looks. Then there is the possibility to do some modifications, if the result is not desired.
Thanks for the pics, they help a lot. It's great to see where you guys usually cut the body and other stuff like that. I will be using those for reference for sure.
I wish there would be more pics of '60 Impala Pro Modified but I guess that it's not the most common body. Though seeing other Pro Mod bodies and comparing them to original ones helps also, since it is possible to see where it has been stretched/shortened, cut etc.
Pretty much what Wayne said is better advise than mine. Pro Mod is the creative outlet of drag racing. Research, get a vision and create it. That's where the real fun is.
Well I wouldn't say that. Both of you had excellent advise and both replies were really helpful. I think that with combining the 1:1 measurements and looking at the result, maybe doing some modifications to get it look better without looking at the rulebook, will lead me to the best results.