Hi Jason,
I'll join the Team here to help out.
I've taken a Bose Lifestyle 38 apart and repaired it many years ago. A good friend of mine had one on his 40 foot Cabo Sportsfisher, and the DVD portion failed. The reason I repaired it , rather than replace the whole system (The Bose Lifestyle 38 was the "stock" system that came with the boat when he bought it new) was the speaker wiring would have been impossible to replace without ripping the main salon apart; which would have been a massive undertaking. The Bose Lifestyle system was okay for a Boat, and probably better than most; which isn't saying much as most boat systems I've heard rarely make it up to a good car stereo level. He sold the Boat last month and has a new 29 Foot North River on order for May.
The issue of you using the Cube speakers again is they are not compatible with almost any Receiver Amplifier. They are nominally about 2 Ohms if my memory serves me, and designed to be fed from the Subwoofer that comes with the Bose System. Bose has been very resistive to providing real Data and samples for independent testing & review; so confirmed data is hard to come by. I'd also be concerned about the wiring. Not that it can't be re-used, but check it's size (diameter) and estimate the length of the run from any new Receiver so we can comment on suitability.
Jason, please also provide a Budget number so we don't go in the wrong direction. How many speakers are you looking to use, and of course as per
@Pogre , what about Subs?
I hope this is helpful.