Well, if it truly is a 350 (5.7) vortec than your 6.0 Denali headers WILL NOT WORK. The 5.7L vortec has the standard small block chevy exhaust outlet. O_OO_O All of the LS based vortecs (4.8, 5.3 and 6.0) all use a different everything and the exhaust ports look like this O_O_O_O.
As for can you use a carb depends on whether you have emissions testing in maine. If you do, you'll never pass. I think your best bet would be to rebuild your tbi motor, use some L98 heads, good cam 454 TB and some matched injectors, custom burned prom and maybe a supercharger. You'll make all the power you need and still keep it driveable and cold weather friendly.
Just my .02