Years ago I used Gibraltar knock-offs on 12 and 13 toms. They were the same size as the Yamahas, and have the same hole pattern. But, in the Gibraltar version, the plastic insert that grips the hex rod will slide out into the drum - it has to have something behind it. Fortunately, I found or had a bunch of the Yamaha backing plates, so I used those inside the drum, which solved that problem. I don't know if the Yamaha mounts still come with the full size backing plate or not.
I also used the backing plates on the OUTSIDE of the drum, so, two backing plates per mount. It's been so long I don't remember why I did that, perhaps the mounts left a slight gap. Or, more probably, maybe the Gretsch hole is so big there is no wood to drill through for some of the mounting screws, so I needed the backing plate outside so the mount wouldn't skew around.
(btw, I had used Ludwig L-arm brackets on these drums for years. I bolted the Ludwig bracket right onto the face of the Gretsch mount and used steel bar stock inside as a backing plate. Kludgy, but worked really well. Using backing and/or facing plates, you can use just about any mount.)
Bottom line, I'm sure you can make it work, but you may have to fabricate some sort of plate. Also, I'd recommend using the long pre-YESS hex rods if you're going to do this. The YESS arms may be too short.
How many toms are you looking to convert? What about the bass drum mount? Those Gretsch used 1" holes. The Yamaha down-tube is 7/8"....
A friend of mine removed the ball portion of the mount then mounted a different bracket using the chrome part of the Gretsch bracket as a mounting base. Perhaps something like the INDe mount could be used over the Gretsch part using the original holes and also giving the tom RIMS-like isolation.