ls1ramair19

Hi new guy here just be came the wonderful owner of a 1970 SS 396/375HP Nova from my father... he has had it since day 1. Here is my ? I want to keep this car on the street I already havea race car. and being its one of the rare ss 396/375HP I really dont wanna take the engine out and put a bigger motor but I wont more HP than 375. I have a 468 race motor that i could convert back into a street motor and it would make some real nice hp prob around 600-650. My question is how much horse do you know of guys making off the 396 blocks. I would at least like to make 500hp if not more. I know throughing a nice set of alumnium heds would diff pump up the HP but im just not quite sure how much these blocks can hold. And I kinda wanna keep that 396 orignal style going because I havnt come across any other ones yet. Thanks for any input Devon