Oh My! You seem to be up against it at every step of the way Paul. That's no fun is it?Ok last horror story [ I hope ]
The seat mount when added will severely restrict access to the centre of the rear axle , cassette & diff so I need to ensure they are correct and working before the rear upper mount is welded on.
Now I am very worried about the rear mech mount ?
I remember DannyC having problems with to little chain wrap causing skipping [ not him silly the chain ] the hanger is displaced both upwards and rear wards from it's normal position.
The new R cars have mounts like this
and the pivot sits directly underneath the halfshaft
this looks different to mine as the R cars axle is in front of the rear cross member , on my H car the axle is behind the rear cross member
I will have to see if some holes exist for a mount fitted like this , instead of the welded on piece , which probably won't work reliably if at all ?
I hope you can find a position for the changer that works OK.