You'll have to make a new DC filament supply. I once posted a mod for the ParaBee to get a DC supply using the 6.3v winding, Schottky diodes, and a choke-input filter. The voltage was barely enough (I got 4.8 volts) but it worked pretty well. It may be practical to use the FC-1 choke wired for 2A3 (to get the DCR low enough) which would give a modest voltage increase over the specified 0.3-ohm Hammond 155B. Here's the post:
http://bottlehead.com/smf/index.php?topic=4266.msg39280#msg39280You'll also have to reproduce the ParaBee high voltage power supply instead of the Paramount's PC board. Tricky to get that over the transformer, especially if you do the filament mod.
I assume you are retaining the excellent Magnequest TFA-2004 and EXO-003 plate choke. You should have adequate room for the TFA-2004 on top (make sure it's centered fore-and-aft on the PGP8 centerline). That will leave some room where the Paramount OPT was, which you can use for the HV supply.
On the other side of the power transformer, it will be a tight fit to get the EXO-003 installed and centered, since it's larger. It must go under the chassis for safety reasons (exposed high voltage terminals).
With the "soft-start upgrade" kit for the driver, the rest looks fairly clear and easy if you are somewhat experienced.
