I wish my ST-70 came with the real Mullards. I replaced the red-plate-y East German EL34s with New Sensor built Mullards and a Groove Tubes GZ34 which is Russian and looks like a real Mullard internally. The 7199s are RCA built and might be for sale when I put a new driver board on it.
Buy a Rek O Kut or Empire platter/bearing and stack three rega plinths together. Add washing machine motor and v belt for maximum PRaT….
I’d do the upgraded platter/sub platter if it were mine. The plinth you described sounds like a good idea too.