360 crank in 318 block

No need for custom pistons if you are not going to be super hard on this thing... Silvolite lists some cast low compression 318 truck pistons, PN 1278, that have a compression height of 1.658". With the 3.58" stroke, that puts the piston top at .029" below standard deck height at TDC, much better than the standard .070-.080" of the low compression LA aftermarket pistons.

No eyebrows as mentioned, so that needs either care and limits in cam selection or perhaps some machine work. I'd try to buy one and check the thickness of the crown. Being an older heavy design, it might be OK to mill some out of it.

Re-balance with the external 360 weighted parts (damper and flexplate/flywheel/TC) looks to be pretty easy: The standard bobweight of the 318 piston/rod's is in the mid 2100 range for the heavy 318 rods and the 360 is just a bit less: I have a 2162 grams (318) vs 2150 grams (360) in my data. That difference in within the reputed factory tolerances. I'd consider just drilling some extra holes in the damper and flexplate opposite to the weights to get that small of a change.