I haven't looked into the NG1 but I'm assuming that like the NG3, it has four spider gears which should be plenty strong. I didn't see the 071 suffix in the workshop manual (
http://lotus-europa.com/manuals/misc/ng.pdf) so I couldn't get the ratios. Could you have been mistaken? The suffix is on the aluminum round tag bolted on the rear of the tranny.
I'm making an assumption that the end covers for the NG1 and NG3 are similar. That being the case, Lotus Supplies should be able to supply a rear mount set for your NG1. Given that you can weld, I would think that any modifications you would need would be pretty simple. The kit consists of tubes to be welded into holes you drill in the rear hoop. Mounts with bolts that bolt on to the end cover, and mounting bolts. You'll also have to delete the mounting "ears" that are on the rear hoop. Lotus Supplies should also be able to supply you with a shift linkage kit that will require some welding.
You'll also need a new pilot bearing which, you guessed it, Lotus Supplies should be able to provide. There is a website that spells out all the modifications that are suggested for adapting an NG3 to a Europa (
http://www.greytower.com/jon/lotus/europa/gearbox/gearbox.html). They may or may not apply to the NG1. A call to Richard at Banks might be in order to get the straight skinny on that. I will say that I got my NG3 from Richard many years ago and all I did was install the pilot bearing and bolt it up to the engine and frame.
I hope that helps...
