The M255HV294S is used in the P400's due to the different oil flow in the girdle compared to others.. ... The spacer is machined for even taller gears.. I shim the spring a bit myself...
The only wet hole is the d/s lower hole, you can feel this with your finger inside the hole... the others are blind holes, if you pack sealant where it isn't needed you could push the bottom of the hole out and damage the block...
You can match that little bit and grind it if you want, if you line it up before tightening the bolts it won't be like that.
As for the w/p's, this is how to tell a higher flow vs a standard flow pump tight is high flow, a gap like the flowkooler is lower flow...
FYI, flowkooler now has one...
My advice would be to replace all bushings and start over with the balancing to confirm things are in spec.
If 1 bushing was damaged you may not notice the others are until it's too late, build once and have piece of mind...