I would love to but the old covers are center bolt and the new heads take the perimeter bolt covers.

I forgot you went to perimeter bolt pattern. There are stock and stock type perimeter valve covers that are dimensionally the same as the center bolt style that should work. I can't tell from the pictures exactly where the clearance issue is but another option, and its not too eloquent, is to dimple out the the areas in question assuming it doesn't conflict with the rockers.

I understand your frustration as I nearly had the same dilemma until I had that "a ha!" moment getting the stock covers over full roller rockers thus clearing the GLMs too.

I ran unto the same issue when I switched to Dart heads & a full roller setup with stud girdles, I ended up heating & putting a dimple in a cheap old set of covers then bought a nice set of aluminum ones from GM Performance store they fit perfect! kinda a weird shape on top but the look great a little pricey I had to buy (4) Summit Racing Part Number: NAL-12480127 good luck!

No. Perimeter style.

That looks about what I had hopper. I ran the 3/8 header flanges for a few months, then finally had enough money to buy two pairs of emi thunder manifold and long tails, those have plenty of room with no spacers.