Definitely do not remove the shims! If you choose to stay with the lip seal, you'll need to trim the shims to let the ends of the seals butt together, and maybe add a strip of shim stock behind the seal pieces in the block and the cap. A little brush-on sealer like Permatex Super 300 on the back side of the seal halves might be a good idea, also.

Or, you can use the rope seal. It's not uncommon to get a slight amount of seepage with the rope seal, so if a few drips on the garage floor upsets you, better make the lip seal work some way or another!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!