I'm with mcjnic here. I know people weren't thinking about collector's value back then, and I'm all for functional hardware, but that Pearl stuff isn't pretty and it's tough to position. Nowadays, of course, we'd just use suspension mounts and avoid messing with the shells, but back in the day, there were still better options. Tama had great hardware in the 80s.
As for putting a value on this kit: that's a tough one. The Pearl hardware, and the fact that they are concert toms, hurt the resale value. But they're still Gretsch drums. And hey, if Gretsch concert toms are good enough for Phil Collins, they're more good enough for me. I'm not sure what they'd sell for, to be honest.
Me, I'd be tempted to convert them to double-headed toms, remove the Pearl hardware, fill in the holes, and rewrap them to cover the work. Since they've already been modified, I'd think the standard reasons not to mess with a drum don't apply. Others might disagree with me.
I don't know if you'd make back the cost of modifying them if you went to sell them -- Gretsch lugs and die-cast rims aren't cheap, and the wrap would be a couple hundred dollars or more -- but you'd have a great player's set of Gretsch drums.
For me, the bottom line is that these drums have some issues, but all Gretsch drums are special in my eyes. I like 'em.