I've heard a number of times that you can shoot .32ACP in both .32H&R Mag and .327mag revolvers. I still have some .32ACP from when I had a NAA Guardian and don't see buying another, so it is a reason (one of many) that I plan to eventually buy either a .32H&R Mag or .327. So, I suspect you'll be fine, though you wouldn't be able to quickly reload if needed (the extractor won't catch the rims, since .32ACP is only semi-rimmed). You may want to try it at the range before you actually carry it.
As for which will have more penetration, neither are great on penetration. From what I can tell looking online (there aren't a ton of .32mag gel tests), both are pretty close (10-12" is pretty common). Though, with JHP, the .32ACP is more likely to be more limited in penetration, and if it penetrates, it is less likely than .32mag to expand. Personally, if I had a .32mag, I may use .32ACP for fun at the range, but I'd use .32mag JHP for defense.