Just straight frame bracing won;t change the geometry. But if you Wanted to start almost clean sheet, there is a way to do that...JCW and trails, I'm willing to put in that kind of work. I mentioned this in another post but I went to school for that kind of work, although automotive. When I graduated I worked as a metal fabber and welder until one of our economic downturns. Now I just do that stuff as a hobby. That said, commenters on this forum have highly suggested I don't go that route due to many people messing up the geometry and making an unsafe bike. And it sounds like there would be lots to modify on my frame to get it to z1 spec. Is it worth it?
basically hang the frame on a gantry type structure. Attach the forks and swingarm without shocks and raise or lower the front and rear to where you want it to be. Geometry wise. go from there to figure the needed shock length and check clearance for chain etc.
Oh yeah and it’s trials, not trails... type of motorcycle/riding