I know Mike's going to hate me for this but I vote 400 stroker. There's lots of these blocks around for cheap, get a good set of 452 heads or 902 with the hardened seats and build that puppy from the ground up. I'd say you could do it for 4-5K depending on how much work you farm out. Either way if you go to a 360 or 400 you're going to need larger torsion bars for highway handling, 3 pass rad. (you're near Vegas) and I'm guessing you've got the 8 1/4 rear with highway gears like 2.75 to 1 that came with the slant 6. Therefore the rearend will need some money spent on it to. Remember it's only money and speaking for myself Big Blocks are good for the heart, kind of like Viagra without the blurred vision.