good one Niko! nothing wrong for going to fast, next time you can lower your dial in time. Anyways back to your questions, some really good advice from everyone. Now I checked out the fit of the pro sportsman chassis on a Revell 60 and there's going to be a fair bit of modifying to get it to fit, so personally I think you're better off scratch building it . Now I'm no expert but I think if you follow my camaro build
http://www.modelcarsmag.com/forums/index.php?showtopic=74760&page=1
anyone can build a reasonable representation of what these cars should look like. By all means use styrene, talking to a modeller friend while I was away and taking a couple points from Dale's mustang build I may go back to styrene cages soon as well. Its not hard, break each section of cage down ie main rails, floor support, main hoops, drivers cage, back end etc. Each section isnt so hard broken down, it only as a whole that it looks confusing.
tried the pro stock pontiac chassis as well, way to narrow and too short a wheelbase, also harder to modify imo