You could probably do that with a nice 70mm or definitely a 76mm

 

I'd go 408, not that much more expensive for the cubes you're getting. Ill be building one sometime this year, procharged though instead of turbo. Just gotta figure out what I want to do for a rotating assembly.

 

theres a few PT88s on a 370, heck flaco ran one on his 370 in little sis, cant see it being to big, cant see it being to much for the street! heck theres a PT88 on a 6.0 running around town here and its a true street beast! imho i think it would go well on a 408 then again what do i know about turboes lol

 

Id go 365~370 unless you want to try and run 9's on 91 octane. A 365 and S475~S480 is enough for 10's easy at that elevation if things are right. I recently went 10.1@132mph at 5000' elv with stock bottom 76mm 6.oL, and a plug wire half off the plug. Also forgot to lock the converter. On 8cyls it would have been 9.90's.