I'm riding a double crankset right now on a bike I inherited. 52/39 shimano 600 (precursor to ultegra).

Or should I say it's riding me. In the process of getting in shape and building strength back, I'm having a hard time on even mild hills.

I'm considering either:

a compact double crankset (like 50/34)

or a triple.

without opening a can of worms on virtues of double vs. triple (not interested) I would like to know if there is any compatibility with my cassette and derailleurs that I'd have to consider when deciding. I'm thinking I need to stick with a double crankset if I don't want to change anything else.

true?