Hi Eric, thanks for your message. Indeed, I figured that converting a mono machine to stereo would not be trivial nor inexpensive, but thought I'd ask just in case there was something I hadn't thought about. I have plenty of reel recorders so don't need a mono PR99 at this time.
If I do intend to equip myself with a "Tape Project" compatible machine some day, I'll look for one that already has the necessary configuration. I suppose in a pinch I could consider doing something to my 2 track Ampex 440C, but that may be beyond my technical capabilities.
Cheers, and season's greetings to all!
--Robert