situation; 1957 445 Duett. Transplanted B-18 with O/D from '68 1800.
Compression was acceptable so I didn't open up the engine (my bad).
Recently noticed that oil pressure didn't seem to get above 45+lbs,
then just yesterday it took almost 30 - 45 seconds of running to even register. Shut it down immediately, and check dipstick. More than enough 30wt. in sump.
Install oil pressure gauge at block, test pressure. Same result; takes way too long to register, but eventually does. Conclusion; oil pump is FUBAR.

Question, why does an oil pump fail, and does that mean that everything else in the lower end is also suspect? Knowing that I will have to remove the pan to replace the pump, I will naturally inspect the main bearings, or at least several of them. Where, and what type (manufacture) of pump to buy? Melling vs? Any good deals out there? Is a heavy duty pump overkill on an essentially a cruising vehicle? This car's a keeper, so I'm willing to invest. Any hints on installing and maintaining a new pump?
How about some way to bring up the pressure prior to restarting the engine. Is an oil change a good precaution? Bahdup, bahdup, bahdup! (sound of heartbeat)