LOTS more knowledgable engine guys here. Yeah priming, a leak down and compression test?
Maybe pose the question in "small block" forum? Sorry not trying to get you worried, just better safe then sorry. Not sure if there ever was a quality issue with MRL, I've just read about "inflated numbers"
No 1st hand knowledge, just what ive read.
Do a search "MRL" maybe?
I wouldnt think pan or heads need to come off.