I suppose this is a cautionary tale about trying to mix early and late systems.
My van is a badly converted 1983 panel van, and I tried to fit a 1987 DJ complete into the engine bay with early cooling system and exhaust.
The exhaust is not a problem... it all fits nicely.
I understand that the early exhaust loses about 10 bhp compared to the later exhaust.
The plumbing on the other hand does not fit.
The air-filter housing and the air-flow meter both take up the same space as the big fat early coolant pipes.
The water pipes fitted

The air filter housing fitted
Note the white hose clamp in the photo.

So now I am thinking that I will have to convert to later cooling pipes.
Oh joy.