How important is measuring and then shimming for end play?
Would it cause a major problem to just replace all of the front flat bearings and then use the V shim?

 

I am not very knowledgable about rebuilding, but I do know that when the previous owner of my girlfriends car rebuilt it, the reason it had low psi was because it had no end play and the corner seals immediately wore a deep racetrack around the irons. When rebuilt with lots of new parts, my rebuilder showed me how the end play is supposed to feel. Yeah.

I can't comment any more on the topic as that's all I know. I'm not a rebuilder.

 

more likely a damaged or crunched front bearing that slipped versus one that was too tight initially.

oil pressure drop would occur after the front stat gear bearing eats up the debris from the front thrust stack and dumps it into the front rotor(the loose bearing would eat up all the oil pressure before the rest of the engine), which also incidentally could cause the damage to the front iron friction surface.

if the thrust play is out of spec too loose it probably means your thrust shims are grooved and should be replaced. this is relatively common for engines that see alot of city miles riding the clutch pedal or engines that just have a lot of mileage.