The issue you will have with any SBM is crank weight. My billet 3.79 crank weighs 63#'s. Stock 3.31 crank is 57#'s as I recall. The typical SBC dirt racer can get a a 39# crank...makes a ton of difference.
I tried to get a lighter crank built... talked to SCAT, Windberg and Bryant. Lightest they build is over 50#'s. Six month wait. And several thousand dollars.
I'd spend my money elsewhere.
BTW I have a 13.5-1, 388" 360 with W2 heads running on moonshine. Crower billet rods. RaceTec pistons. The next build will be a 340 +.060 with a 3.79 crank, Brodix B1BA-MC heads.
