Bad news I'm afraid, the mountings are in different places on a 43F.
I have a couple of 34L Teneres (which in the UK have a bit of a price premium on them)
I also got hold of a 43F (because in the UK they too are seen as plain Jane and a bit less in demand) - I was either going to use it as a source of spares for the 34L or do the as you and put the 34L tank and bits and bobs on it.
Of course it is doable but it would be a pain in the arse as the 43F and 34L are subtly and minutely different in a lot of ways, particularly the tank.seat/side panel fitting arrangements
43Fs can be a good source of spares like rims and engine internals and hubs and so on but it is not possible to swop body parts unfortunately
I love my 34L Teneres - they truely are the King of Bikes