Can small block oil pump be replaced without pulling the engine?

Rusty may be right if you have an engine hoist and engine stand, the extra work may be worth it.
What I will remind you of, is when you roll that engine over, all sorts antifreeze you thought you drained gets all over the floor, - so do it outside, cuz antifreeze doesn't evaporate well, sqweegee/mopping may be nec., so you're not rolling around on a wet floor, been there. Don't let pets/animals ingest any antifreeze ! !
I live on a farm, so the poisoning of any living thing can end up as food for something else to eat, it cruelly blinds them first, so caution .