looking for a set of front discs/spindles/calipers/etc from a late pv/122 to convert.

anyone have anything kicking around?

Heard you just got a couple of 544s and fixing one up, as I can tell from your plea for discs. I was wondering if you were parting out other car like a windshield and left front fender. I might know of a 122 gradually being stripped down here, I'll ask around and see if it's still got the discs.

Get aftermarket stuff- the 122 calipers are expensive, heavy and prone to seizing. The rotors are heavy expensive and prone to getting the shakes. Ask me how I know.
One of the top three worst mods ever, along with electric fan, and Koni's.
Don't.

How do you plan to get the balance right without a booster? You can't. Not with all the adjustable valves in the world.
How to you plan to get the pedal effort tolerable?

I don't know the exact parts I'd use if I was doing it again, but I certainly wouldn't do the OE 122 stuff.

Regardless of the "issues" with the 122 brake components, I'm not sure where you're coming from with the other stuff. The vast majority of people running stock 122s are running without a booster. What does it have to do with balance anyway? It's a single circuit system. If I'm not way out to lunch, the 544 and 122 have the same rear drums, no? If pedal effort is too high, Wilwood makes a bunch of master cylinders that bolt right in. If the balance isn't right, 1 front/rear adjustable proportioning valve is all it takes. You make this sound like you're trying to build the Mars Rover...

The Apple Farmer Racing Carrera Panamericana race 122 has Wilwood calipers bolted to the stock spindles and uses stock rotors. Not sure what, if any, modifications were done but I can't help but think the front/rear balance must be tweaked with a proportioning valve.

You don't need a booster for brake balance. I managed to achieve balance with my aftermarket Wilwood set up by doing a little head scratching with the engineers at Wilwood (no valves). It's a matter of piston size, rotor diameter, vehicle mass, desired g-force, and master cylinder size. We got it all worked out with 4 wheel disks and my brakes are awesome. Max effort stops (just short of loosing adhesion) and everything pulls down even. If I go past that point, then the rears lock just a fraction before the fronts.

In general, Ian's got it nailed - get the old stock stuff out of there. I initially did my Wilwood conversion because it cost the same as replacing/rebuilding the stock stuff. The upgrade was a bonus.