It seems like a long shot that someone hasn't tried this already, but wouldn't it be easier to replace the lower timing gear to fit an easily available cam gear? The D-series ones seem pretty common/inexpensive.
I would think as long as the ratios are the same you could get a belt that fit to make it work. Just have to find a lower gear that is the same or close for inner diameter and work with it. Seems like less work than finding a adjustable for our cars atm
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