550 horses would squeak 3800 pounds into the 11s if all things are perfect.I would aim for 580 hp and make sure the driveline is strong.
If you want the cat to be street able and not totally race oriented,I would build a 540-588 will a roller (hydraulic) and use dart 335s as a base to work with. If you want to stay away from rats,then My next choice would be a twin turbo LS-3.
If you dont want efi,then use your gen 1 with a blow through.Turbos have a very "cool factor" to them.If you use a blower,then make sure its fast or people laugh at you.
example here,350 rat rod/dual AFBs on a 671 best time ever 12.01. Good thing its a rat rod