No if any conversions at all for Urvans Ive seen is they are converted to L series rather than U20 but U20 is a better motor for durability.

All Urvans had the U20 then later ones used the Z and Ka while vanettes A15 are rare now but also later ones are Urvans with Z series usually.

You will still find an old U20 urvan somewhere trust me they are round more than fairladys, Ive seen still plenty on the road with one old couple that use it for markets clocked over 1million kms.