A note on the half fill, I was looking into it pretty deeply for my build (also same goals, 650-700hp for a street car while attempting to keep the RPM's low only I'm using a blower instead of a turbo).

Hughes told me don't bother with it.
My machinist, a very knowlegable NHRA super stock record holder said don't bother and stated there was plenty of meat in the lower bores of my 340 block. I had actually paid him for it and he called me up asking if I wanted a refund telling me he didn't think it would provide any benefit.
I have also talked to a few people making 600-700hp with lower rpm forced induction builds who did not half fill and had zero issues.

There were, of course, a lot of guys that I found who DID half fill and had SBM's living at 650+HP. I'm still on the fence on whether or not I did the right thing by not doing it, but I do know that it probably saved me from some potential oil temp issues.

I just don't think I've seen anyone yet who had a high HP, low RPM forced induction SBM fail because of issues that could be attributed to lower bore distortion or anything that a half fill could have prevented. I've never seen anyone talk about problems they had with a turbo/blower motor that were solved with a half fill.