In my opinion, for what it's worth and not knocking the Datsun conversion, the Moss kit is the way to go if you want everything needed in a box. It's very complete, with all the things you'll need. Just remember, these conversions are not for someone to do that has limited mechanical skills. Once these (KITS)?, are installed, there are other adjustments that have to be made. If you have never done it, check with those who have. They've been there and can give you valuable information and tips that will make the job much easier.
I will say this, there are no more Datsun 210s available. You might find one a private owner has, but the junk yards are out of them, so parts availability isn't the greatest. Another sales point for the T-9. JMHO. PJ
I might be wrong, but I heard Skyhook, one of those who made the 210 conversions, are done. No more transmissions. Maybe they went to something else??