John,
I'm not too sure how round any of these housing came from the factory. Due to the design of the front housing, the rubber bushing will "flow" into the void left by the two piece stamping.
The rears are better designed since it is a continuous circle.
To be honest with you, I don't know if the flowing is a problem with the engineered plastics. If it did happen, one could always fill in the void with weld or even a metal filled epoxy.
Also, make sure the surface of the A-arm is as smooth as possible.
If pitted or the powder coating or paint looks like an orange peel, I'd smooth it out with 600-1000 grit wet/dry sandpaper.
Probebly overkill, but hey, don't we all just get a little crazy once in a while in the details??
