Triggerfish, those are the coolest looking valve covers ever! I've seen similar ones with no logo, but never with the fins running all the way across them.

Not to hijack your thread, but do you happen to know if yours have the long rectangular recessed area inside where "holley - mickey thompson" is usually stamped or cast in?

I ask because I have a set exactly like these on ebay in the garage back home. Ebay Holley M/T valve covers (not my auction - just for reference) And I was wondering if there was enough material left to machine off all the fins, M/T letters, and the long raised rectangular pad on the outside and just make them smooth. I was thinking about going with fabricated sheet metal ones on my motor but I don't like the unfinished welds on all of them. Though they might look cool and different with smoothed tops and the blockier look to them.

Did find this on a brand X forum for you. Looks like actually knocking out the "knock out plugs" is frowned upon. I was going to guess if they were vintage they might be more prone to cracking from an impact than new ones also.

M/T valve cover topic on nastyz28.com

Ummm... ahem, wouldn't want to trade would you? Awesome find on those.