I'd say if you have to get a new shortblock, get the bigger cubes even if the supporting H/C/I are on the small side for it. Sure, it won't be on par with cars with the properly matched HCI for their strokers, but it'll make more TQ and be a better platform to build from than a 306. I went with a 331 for one reason and one reason only, the turbo kit I have had a relatively small turbo for it and the 331 would work well with it, and with the T76 I have since upgraded to. It was a compromise because I didn't know what turbo I'd use when I built the stroker. If I had to do it all over again I wouldn't have bought the turbo and I'd have a higher compression 363ci NA setup.