New alloys, old Chevy.

Hi all!
I have a 1980 Chevy Scottsdale 3/4 ton. I recently bought a set of the HD Duramax style alloys to go on it. 16" 8 lug. Wheels fit great and look awesome. Here's the problem. The center cap... The lugs for the old truck are standard, and I assume the new ones are metric. And I have to have the newer lugs in order to use the center caps. What are my options? They don't make a lug that will fit both the cap and my truck. I've thought about changing the studs, but that isn't cheap and not even sure if that is the correct answer to make it work. I have even considered retap of the studs or the lugs. Any thoughts? Or am I just up the creek with this? Don't want to spend a fortune on this. Thanks for your help!

I've changed these studs out before. I don't remember it being that difficult, or expensive. I wasn't changing from one STD to Metric, just replacing damaged ones, so maybe my experience isn't valid in this situation, but I'd look into it. Maybe someone else with more experience will jump in here.
Good Luck!