Check the conversion areas carefully, some don't get rustproofed properly.
Have a look at the fuel tank. Often made smaller to allow the dropped floor. A problem if you need to do longer journeys as you'll spend a lot of time in filling stations. Also check any fuel tank work has not created any fouling conditions.
Some have a folding ramp at the back, which can rattle. Others have a single piece, but it then obscures the rear view.