I gave up mate. It would be easy to do - that is make up a bracket/plate to fit the seat slides and have the holes drilled to suit whatever seats are available, but it was the whole engineer approved thing that put me off....that and the cost of good seats
I found the racing style seats little better and really hard. They would need almost total reupholstering.
I think I was on the right track with hunting down wreckers for quality seats though....many are electric as well and wouldn't take much to wire in
then they will adjust in many different planes and you can usually find a decent setup.
Thinking late model Statesman/Fairlane etc.
I guess now with the number of not quite legal mods like tyres/wheels etc I should just make a solid adapter plate that I know is strong enough and be done with it....bugger the engineering.
In the interim I found the seat spacers and an inflatable lumbar support has worked OK.
Would be nothing like a good seat though and wouldn't do for long drives.