Need SB or BB Suggestions

[MARCUS'S 68]

Ok guys need a little help here looking to build a motor for my 68' looking for serious horsepower but nothing wild looking maybe 500-600 hp. Goal is to play around with these sports cars want to eat em up on the street. I have my buddies say go with a 377,383,400 kinda confused something I want to build myself have spent serious money on what was suppose to be built motors and when i got it was half the HP. I have built a 468 BB Blown 1234HP but thats way to much for what I want still want to drive it everyday but want something reliable. Right now have a 4.11 Posi and 350TH tranny with stage 3 B&M shift kit. I am leaning towards a 383 all motor but all suggestions considered, and if its not to much to ask after all suggestions are reviewed would like to ask the lucky conestant for a full build sheet. Thanx to all who took the time.