You want to stay within normal sizes for cost issues. Oddballs (meaning over .030 beyond factory bore) are considered "custom" and more $$. I use Diamond. Use the dished pistons, at zero deck. Keep the overbore at .030. The more you leave the better. Seeve that one hole if it's rusty. I sonic test every non-stock stroke combo. I would do yours. That right year yes, but you dont know until it's checked if the guy building the castings got the cores in the right spots. I dont think a mild oported set of RPMS will reach anywhere near 290. Closer to 260-270 is more realistic assuming they were ported and not just sand rolled... That last 20-30 cfm takes a bit of work to reach 290-300. For low 12s, a cam in the 245-250°@.050 range with lifts in the .530-.550 range will work fine and make mad torque. A roller is nice, but I just did a similar one using a hydraulic flat tappet cam and it's fine and in a 3700lbs car with 3.23s goes 108+mph in the 1/4 on street radials. Iron heads, pump gas.