"In the past I have driven the oil pump by a drill and adapter to make the engine lub. can this be done with an L-head."

Yep, it drives through a gear on the distributor shaft.

It looks like you have seen all of the "Best Practices" posts, so you have a lot of information. Just don't force it - it should turn over with fan belt tension and take it slowly. Haste makes expensive mistakes sometimes.