Currently I've got a G4 733 board on my workbench I'm putting a 1.0 on, I sadly don't have any 1.5s or anything, for 745x CPUs they're expensive over 1GHz, but I'll probably overclock it to 1.2 or so.
I've also got a PowerBook 604e experiment I'll try soon, along with upgrading my G3 CPU cards...