Big block mains, I fitted BBC four bolt caps center three, a full width BBC two bolt on the front, BBC two bolt rear cap. Line bored and then line honed. Re-drilled pan rail and used BBC pan. Timing cover upper two thirds, 409; lower third BBC. 6.385 rod, ring pack squeezed together a little, counterweight OD reduced .200", required several slugs of Mallory metal to balance. If I ever get retired, I will finish the engine. Bob Walla raised port heads, 3/4" spacer plates, M/T CrossRam. Many of these parts were leftovers in the shop. All the machine work was done without CNC tools.
This kind of project will soak up a lot of enthusiasm.
I have also built a 476" engine with BBC size journals and caps, done a different way.