Brent -
Where ya been, Dude? I haven't seen you around town.
One of the toughest parts of LSR is decoding the rule book. The basic answer to your question is - "Yes, your car is likely eligible for numerous classes". Variations in the body - really, in the aero - can move you around in the class structure, as well as the fact that you probably qualify for several classes that you can chose at your discretion. With my Camaro, for example, I can add the flat rear spoiler and front air dam and "PRESTO" - it's a E/CGALT car. Remove the dam and install a stock Z28 style spoiler (a bit better than nothing)(or no spoiler at all) and it's a E/CPRO. So I can switch back and forth pretty easily. As previously noted, belly pans and other mods will move the car around in the class structure, too.
As far as engine mods - pretty much anything goes. You can run "PRO" as long as the port configuration of the engine matches what could have come in the car from the factory. I can run my six, a traditional SBC, or a BBC. All I have to do is declare the actual displacement and select an engine class accordingly. I CAN'T run a V6 and stay in PRO - it was never offered in that body. So your 305 is fine. The blower, however, takes you out of PRO unless you remove it and run in that configuration (been done, btw). But ANY cam, intake, etc. is OK. I don't think PRO allows EFI - I run CPRO and I KNOW it does not allow it. And on it goes.
I look forward to seeing you there!
Dan