My 1998 H150 was fretted with Dunlop 6100 (measured with a micrometer), or some equivalent since Jescar and some others make the same size fret wire. It has always played very, very well and it had that resonance acoustically when I first picked it up at the Marin County guitar show 20+ years ago. I bought it on the spot from Buffalo Brothers, who at the time were a big Heritage shop. They said it was a special order run they had made with standard tail piece and SD59, the jumbo frets and no nibs. The original owner had traded it in for something else. I've not really done much other than play it most of that time. It was always a little dark, but when I had to change the output jack, I found they had also used the late-70's era Gibson pot values of 300k volume and 100k tone. I just re-did it all since I was doing the jack. (those enclosed barrel jacks tend to fail).
I recently put it on a diet, put on Gotoh SG301 locking tuners in place of the Rotomatics (perfect drop-in fit) and half the weight, which took almost a 1/4-pound off the weight of the guitar! Those Grovers are heavy. Also put on locking Faber aluminum tail and bridge with the inserts. It's now down from a little over 9lbs to about 8-3/4 lbs, which is a lot more pleasant and balanced. Locking tuners and hardware make string changing so easy.
I figured the 6100 fret wire would be good on the H535, they feel great and leveling the fretboard was the key. I didn't have to do much to level the frets after installation. I was stunned at how much better it sounded when I installed the longer Faber bushings for the tail and the bridge. They just really made an enormous sound difference in the 535. I think it just coupled the vibrations well into the maple center block, where the original Schaller bushings were much shorter, making little contact with the core. The bushings had little effect on the H150, as the ones that were there were pretty good actually, longer and securely pressed in.
I'd recommend the 6100 wire. It's the biggest and smoothest that doesn't feel weird. I have another guitar with the even bigger super-jumbo Dunlop 6000 wire and it feels "train-tracky" to me.