Feel free to. MOST AMT kits are quite buildable, and many of us have been building them for 50 years or more.
I've never built the kit you're talking about, so can't speak to it, but I just started work on AMT's Snapper '53 Vette--essentially, an unassembled promo--and don't foresee any problems with it. By coincidence, I just found what seems to be the up-top from the kit you're working on in a bag of random parts I bought at a show, and I'm going to try to make that work with it, though it looks like it will need some minor "tweaking" to fit.
Model on!