Best 273 and 318 builds (NO 360's please)

I think the problem you'll find with a stroker is that the bores are so small, the rods may interfere. Assuming using the same pistons, but wouldn't the larger stroke raise the pistons in the bores causing compression to increase? Or do I have it wrong?
Yes, and it could result in positive deck height too which would not work well. You'd have to start way with pistons way down in the hole or some folks shave them. The size of the bores won't matter much- you won't have perfect clearance stroking a 318 or 340 either. The 360 crank would likely be fine, but the 4" would need clearanced. As said- it'd take a lot to bring the compression down to something reasonable.