I am looking at the same idea for my Yam.
I'll second Nos here, because I am trying to get the old tilt lock lever out (it's sheared halfway and one half has wedged itself nicely in the hole)- It would be safe to say I'm probably going to have to hacksaw & drill the old shaft out. There's an even bigger rusty pin holding the tilt assist ram in (what the PTT replaces), and it's so rusted it's staying put without the aid of the long corroded & fallen off spring clip......
Having said that if anyone knows of a siezd / blown up PTT 1980s Yam 50/55/60/70(/90?). do let me know!