This is my first post on here, so be kind...

I have recently found a lot of rot under my Autosleeper high top. I am getting a decent roof put on, and will keep it as a tin top for the time being. My plan is to fit a westy style pop top, at some point, as this suits my circumstances better than refitting the high top. I have a couple of queries..
1. Has anyone else done this using a regular tin roof (the roof cut I am getting is not from a Westfalia conversion)? I am reliably informed that there are issues with a non Westy roof, in that a genuine westy pop top would not be a perfect fit on a regular tin roof, due to the slightly different shapes of a regular roof and a westy roof at the point of manufacture.
2. Can anyone recommend a supplier. I have someone available who can fit it, just after recommendations before laying out the cash.
The ones I have seen so far are from Space roofs in the Southwest and Pop Top Roofs in the Northeast.
Any advice appreciated.
Cheers,
Paul