I have a Morris Van with an A14 and a 5-spd. If you don't have it yet, you might want to look for an A14 vs an A12 if you want a bit more performance out of it.
Here is a NZ-based Morris Minor forum. There is a good bunch of lads over there on that forum! There is a fellow named Fweddy who is located in Christchurch that has a van with an A12. (Same chassis as a ute)
Minor Mania ForumAnother good one is the Morris Down Under Forum. Lots of Datsun swaps with technical discussions. A lot of folks there have done that swap and are always willing to help. There's a complete writeup on it with pics, too.
Morris Down UnderMy swap was a bit different because I have a LHD van with a hydraulic clutch. I also used a 5-spc and the Datto rear axle which doesn't seem terribly common. I am located in the US, and Morris vans are exceedingly rare here, so I went about the swap a bit differently.
I am about to scrub the Datto drivetrain and put the van on a different chassis with either a 4.3 litre V6 or a V8. It should be fun!