DIY DC Generator

[WilloCo]

I just scored a Farymann single cylinder diesel engine from a generator. (The genset side is missing)

I have a 140a 24v alternator that I'd previously stuck on my Beta 50 with a wakespeed 500.
I'm pulling the beta to do a rebuild after having ring issues this season, so it's a good time to rework the alternator on the bench. I can trivially convert it back to 12v since I keep AGM batteries for starting/windlass duties anyway.

So I'm leaning toward stealing the 24v gear that I already own and that works with my lithium batteries and slapping them onto the generator engine.
I can get couplers and make it direct drive, should be a pretty easy machine project to make a mount and marry it to the generator engine.

I am open to better ideas. I do have a three phase BLDC motor on the parts pile that I could use but I haven't found a good high amp controller for charging only.

Thoughts?