Front sprocket looks very nicely done, there was a small company/guy specialized in doing that Gary Poh?
Found his site but it smells of dust n cobwebs. ZERO pics of the conversion kit on a quick look about.
https://xs650widetire.webs.com/
prolly get someone to machine that apart and weld on another sprocket when the time comes.
The joys of custom bike ownership.
I'd be more worried about the type of PO you have, evidenced by the chicanery on that starter gear cover bodge up. That's not the only dodgy work you're going to find.
Were that in my garage I'd be opening motor covers and looking for, removing excess silicone seal BEFORE it blocked an oil passage................
you'd better buy a 6mm bottoming tap and hope like hell you don't have many stripped threads.