Ricky, are they L2291s?
If so, they should be 1.776 CH so the stack would end up at 10.154 or 10.155 depending what you use for rod length value and assuming a 73 cc chamber
- If you deck the block to 10.155 and assume a 73cc chamber, use a Felpro 1020, for .041 quench and 9.68:1.
- If you cut it to 10.150, use the Felpro 8554 at .053 for .048 quench and 9.53:1.
- If you didn't want to go proud on the pistons, then live with the .053 quench, that isn't horrible quench distance and 9.43:1
That combo usually works really well for a mild/budget 390. If they are something else, I would shoot for .055 max quench, but in the .040s preferred, quench won't give you problems but need to look at compression ratio too. Also 73 cc is an assumption
With all that, any of the combos will run a 268H cam on 106 ICL, not smaller or earlier, although I wouldn't pick that particular cam, it gives you a reference point.