You can use HEXFRED diodes for the high voltage. For the filament, I recommend a 3 Amp silicon rectifier. You will have to install a small terminal strip for the rectifiers and be advised that the filter capacitors are shot! so replace them too.
If you are not planning to use the tape EQ, the phono EQ can be moved from the selector switch to the bottom side of the board, eliminating the need for the middle deck of the selector switch. This means that the phono input can go straight onto the circuit board. And *that* means that the low level input jacks can be replaced with a single pair of jacks.
Have fun! but don't go overboard. When the mods get to the point that a second chassis is needed for the power supply or something, you're going too far!
