Not done that but I’ve fitted a late Devon pop top onto a 72 roof panel onto a 1970 van, fortunately everything was more or less the same size. I’m thinking this should be the case with the Westy as well because they were all built around the sunroof model and that stayed the same as far as I’m aware. I’m also wondering if it’s possible to just take yours off and fit it backwards to give you the same effect. I’m trying to think who might know for sure and I’m guessing that Davidoft would be the chap most likely to know for sure and probably the main source of any parts required to do this. I also get confused with which one is which, I think the obvious way for sensible wind closing rather than opening is hinged at the front and rack at the back and the later ones were visa versa but I wouldn’t swear to it. The roofing profile curvature is different from memory but could an adapter type piece be made up to form a curve in the straight rear section and again visa versa.
Ozziedog,,,,,, could be a very interesting conversion
