First time swapping edelbrock aluminum for 915 cast iron heads.

Which 284/484?
In either case, 10.2 is in the ballpark for iron
IMO, you don't have nearly enough compression for for aluminum. At 10.2 you're bottom-end is barely stronger than a 318, and you'll need a hi-stall to get moving in hi-performance fashion.
I'd want at least 11.2 ,perhaps 11.6 with the108LSA, in straight up; that 's still less than 180 psi. That short stroker could run even more pressure.I've run 10.9@185psi on 87E10, in my 367
If you're limited to 10.2,and aluminum, I'd slam the intake shut a lot sooner, like maybe an ICA of 58*. Even that ain't right ...the bottom end is getting disproportionately strong ,compared to the top. You just need more compression.
That's what I think.