B B....same problem here, but different parts. I want the engine case cover that goes from the tranny cover to the base of the rear cylinder...guess what? It doesn't fit with the Lifter Block covers I already have installed (which were a bitch, by the way). I'm going to order the damn thing anyway and take a Dremel to it and make it work, if possible. Kury doesn't seem to have this problem for some reason as all their parts fit together nicely...what a novel concept...to have a bit of foresight. I need the cover to hide the damn weeping, dirty seam that comes back after every cleaning.
TC, there is one other option to consider. I personally think it's a lot better looking.
Yours will likely be apart this winter for your cam (or other) work anyway. When you do that change your lifter blocks. Lose the covers you've got. They are better looking than stock. But they are also kind of bulky looking.
Use these instead. You'll make the appearance sleeker, have a better looking part, and allow all the room in the world for the other part behind it.
I went ahead and did the matching rocker boxes and push rod tubes at the same time. The push rod tubes and lifter blocks weren't nearly as expensive as the rocker boxes though (and they often showed up on eBay pretty cheap from guys that bought them and then found out they actually had to tear stuff apart to change them).
Anyway.... Just another option.