Thor Motronic was allegedly an improvement over the GEMS injection system.
Before going to a lot of swap-over work I would try what
@Datatek said and spin it over for a fair bit with the plugs out and plenty of oil showing on the dipstick and see if you can wind some oil pressure up.
Didn't a new oil pump used to entail packing it with vaseline or the like in order to get it to prime and suck oil up from the sump?
Standing for a long-long time will mean its as dry as a bone. I don't know it you can get oil into the pump from the reverse direction to prime it, so spinning it up on the starter is all that's left.