grouted 440 block

The extra stiffening at the bottom of the cylinders is not a bad idea for a 4.25 inch crank. It also depends on how much grout as well, is it the maximum amount that will still allow water to circulate or a half inch or less? If it's the maximum fill, plan on a flow kooler or similar high volume pump and as much radiator as can be made to fit. Regardless, AndyF is correct, an oil cooler is a good fix and a straight SAE 30 or 40 weight oil has better shear resistance at high temperatures than multi-vis oils do.