Okay, here's the problem... The image you have is omitting a very important part: The front drive axle. Check out this photo from the service manual. The axle is coming through the center of the hub at the right. If you removed the cap (item 6 in your drawing, item 2 here) what you would see immediately under there is the end of the drive axle. You're not going to shorten your drive axle because you wouldn't have anything left to thread the hub nut onto, which holds the whole wheel assembly on.

I know you got a really, really sweet deal on those wheels. But they ain't gonna fit with the center caps. Like we talked about you may want to see if custom caps are feasible or just get the proper type of wheel. Maybe paint the hub or see if a smaller chrome cap will slide over it.