How much clearance stocker rotating assembly.

How much clearance is enough? Did some trial fitting of parts for for my 390 stroker. Nothing interferes, but rod bolts are awful close to bottoms of pistons. How much clearance does their need s to be? The crank counterweight is also close to the bottom on the block in one spot have maybe 0.040 clearance is that enough ? It’s a scat rotating assembly With cast crank and I beam rods.