Hi Mark,
I've got a 1950 C-2, too, and I love it, due to it's beautiful quatrefoil style cabinet. Didn't know there were non ratcheting C-2's, though.
Of course it is possible to install an AO-28 preamp into your organ. But it means major surgery: You'd also have to replace the drawbar base by one from a B/C-3, A-100 or similar organ and to get that percussion switch assembly also. The switch ass'y may also come from a M-3. Last but not least you'd have to move the start/run switches to another place. In other words: You'd convert your organ into a C-3.
Good luck!
Uwe Menrath