Looks to be just where you want it to be IMO. How is the angle of the seat?
I'm thinking of cutting out the factory swingarm mounts and moving them up on my build just so I don't have to come up with something for my chain routing since I didn't drop the engine through the frame and the engine sprocket is way above the pivot.
It's really a hard frame to start with, but it's also good practice. Depending on what I do for a fuel tank I may end up tweaking the rear sub frame to fix the seat height. I checked out your build photos on the other site. I would bring up the pivot points for sure. Due to the swing arm angle you might be able to make up your whole height difference by extending the swing arm. Also, I have no idea if the size is even close, but a 1989-94 or so FZR 600 fuel tank has the same general shape as the one you are making.