Just make sure to confirm standard size passenger car rally wheel caps fit on the 6 lug models. I bought a pair of 6 lug Corvette style rally wheels years ago, and standard caps wouldn’t fit (the hubcap opening in the wheel was too big). The only caps that did fit were special oversize models sold by the wheel manufacturer.
Here’s a photo of the front wheels – 15x6 five lug with a standard police cap:
And here’s a photo of the matching 15x8 six lug rally wheels for the back. Sorry the photo is old and crappy so you can’t see the slots, but it looked just like the front wheels.
Comparing the space between the red rings on the two different hubcaps shows how much bigger the rear caps were. I hated the appearance so they didn’t last long. They may not make these any more, but it’s worth checking first.