I Like the SB Chevy 350s to . But with a 350 or 355 build- even with a set of Vortec heads And a Comp Cams XE268H camshaft . Your talking 400-420 HP . And yes you can go a bit larger on a camshat to put out some more HP . But you will lose bottom end torque doing so . A 400 hp 355 is not a bad street / strip build ! But for what you are Looking for 500 HP you will need a blower or NOS spray on a 350 . But now Lets say you build a 350 into a 383/389 stroker . Now you can get near to the 500 hp you want . And the torque will also be much higher then the 350 build . Now with your 8.5 373 rear end . They are ok stock for the 350 400 hp builds . But much more then that and with 10" tires dead hooking . You will break a C-clip and throw an axle . You will need C-Clip Eliminators . Go with a 350 with-375 to 400 HP build . With this set up and your car at 3500 lbs . That Nova should run 13.10 E.Ts