I would visit some of them, and get a feel see if you like the conversion and the person doing the conversion, we looked at 3 companies down south who came recommended, but we didn’t get a good feel about them, I also looked at two very local to me, one I loved them and the conversion, but the pop top wouldn’t take the weight of a roof box, which was a must for us, the second I had spoken with a few years ago and didn’t like them.
We then spotted a Jaibow conversion with the Hilo Roof, and bought the van as everything was right on the van for what we wanted at that time (the roof and the underslung gas tank)
Jaibow has since added more things and has been ace
But I would say get a feel for the person doing it as you will have to speak to them during the conversion and after.