Less then $100 for a new master cylinder
Average $30 per wheel cylinder
I think for the amount of time spent rebuilding, I would put out the extra cash and just replace with new.
Keep the old parts in your parts bin for emergencies, with a rebuild kit in there for emergency road repair.
My way is not the only way, it's just my opinion and how I would do it, and how I'm presently doing it on my M-37.
My deuce brakes are fine, but prices above are M35A2 assets from your favorite auction house on the internet, and averages, not random prices.
I would consider replacing any brake lines running up to the wheel cylinders as well, especially if any indications of wear or tear.