Wow. He's really altered that pretty radically and there are indeed two reg/rec units fitted. Presumably one of them is dealing with what would have been the AC circuit. I guess he didn't like the whole AC/DC setup.-----------------
Your bikes is a one-off, a neatly done one off but even so... Giving advice will be difficult.--------------
One thing you should be able to test "by remote control" as it were are the alternator windings. The wires coming off this are easy to find, they exit the top of the primary chaincase in a bundle. Follow this bundle and you should come to a clump of bullet terminals on the end of it (or possibly a connector block if he's re-done that too).
Let us know how many wires there are and what colour they are and we can take it from there. No point messing about checking the wiring if the alternator is shot.
Here's a video of me checking for a charging voltage on my 350 bullet. You'll notice how it changes with revs. I've connected into the wiring but you can do the exact same test by measuring volts between the battery positive and negative terminals.