HG's Fix original or swap engine?

OK
I have started removing things, and am grappling with the following decision:
I have a spare engine with the same #Kms as mine, came out of a car which ran fine at the time, has very good cylinder bores, and has had heads off, checked, and new gaskets put on while on a stand in ideal conditions. - Ready to go!
My engine has always had synthetic oil, and the balancer is relatively new.

Would it be smarter/faster/lesswork???? To swap the engine, or to fix my engine which I really have more history on than the other?

hmmmmm

If it were me in that position I would pull the motor put the other one in and take my time with the second motor on a stand.

drop the pan, check the oil, no signs of AF, then keep the motor in, if you know the history of the motor its better IMO, who knows if Bob or Jim got cheap and JB welded a frost plug in on that other block, eh? just way I look at it