I was just planning on doing the rings on my Datsun A12 before putting it back in the car but after I opened it up, it needs a bit more work and parts. So far, I've been able to buy "tune-up" parts such as ignition components, gaskets, etc. but I'm coming up short on internal components such as oversized pistons and a cam shaft. Any direction as to where I can get these parts (new) would be greatly appreciated!

Motor mounts are built and welded in. The rubber mounts are from a Land Rover and will last a very long time. There are nuts very securely welded onto the bottom side of the top of mounts welded to the frame of the car. The rubber mounts then screw into the frame mounts.

Will this lovely 1981 B210 5-speed transmission bolt to my A12 engine?

Well, I busted the rear circular flange of the transmission case trying to get the output shaft seal out. There's a welder in town who can weld cast aluminum but that's this week's sob story. However, I have the engine mocked up in the car to make new mounts during the next two days. The dual SU carburetors look great!

Does anyone have a good source for piston rings? I see that RockAuto does not carry them and I don't really know where else to look. There is an NOS set on eBay but is it a good idea to use 40 year old replacement rings?

Not mass produced, just one for my engine. It seems pretty important to properly cover the transmission with the clutch, flywheel and throw-out bearing being exposed without the cover.

I'm guessing no one makes a reproduction? I guess I wouldn't be that hard to make one.

Does anyone know where I can find a transmission cover plate?

I am in the process of having my MG painted so, the Datsun equipment hasn't received much attention. However, I should be making some engine and transmission progress soon.
I will be getting custom gauges from SpeedHut that match the original MG Smiths gauges but I was wondering what the orange and red lines should be adjusted at for the A12 motor. Any thoughts?

Yes, 1-1/4". I will need to extend the linkages shared between the carburetors and possibly make a new heat shield.