armand, I'm having my original '70 302 block done as a 331 roller with AL heads, forged crank, roller rockers, 9.5:1 compression or so. We've exchanged PMs, but I'm happy to compare notes as I go along. I do like that the '70 block is a bit heavier, but I'm not at all certain that all the weight is in useful places compared to the later roller block. But, it's the original block that came with the car, so I'm getting it worked on. Numbers matching is a nice plus.
The shop doing the build didn't mention that going roller on this block would be overly expensive, and they're going with a 2-piece rear main seal and 1.6 roller rockers, Eagle forged crank, h-beam rods, and of course roller hydraulic lifters. Oh yeah, a multi-layer steel head gasket too that will let them fine tune the final compression by custom ordering the thickness. Those are the details I have right now, I'll let you know more in January when I have more.
I'm with rbohm on the compression, and these guys echoed it. They don't like to go over 9.5, 9.8 at the most on a street engine.
One question I might have is what sort of parasitic loss will I have by reusing my original oil pan? I want to go with a Cobra-style T-pan, but I'm worried it's going to hit my Steeroids rack, specifically the hard lines on top of the power steering ram. I want to use reuse my original oil pan on the motor to mock it up and see how everything fits. I have measurements from another Cobra T-Pan, so once I see the clearance I'll know if the Cobra will fit. How much power am I gonna lose from oil slosh, windage, etc., from the OEM pan versus a Cobra aluminum t-pan?