My 340 in my 66 developed issues :-(

The oil holes feed the rocker shafts. One on each side. 1 8 4 3 6 5 7 2 is the firing order.
Standing in front of the engine the #1 cylinder is on your right front and #2 is on your left. The same as a Chevy.
On a V8 engine, the number one cylinder is always forward of the other side.