Decided to reprint the hotend base which has nearly finished.
Then I can get on to working out the 6025 to 5015 adaptor :)
On my Ender 3 - the X-carriage lower wheel assembly had the nut on the hotend side of the wheel assembly, not on the wheel side as on the two top wheels. As a result, the lower part of the hotend duct needed to be judiciously modified to accommodate the mounting of the lower wheel.
Will let you know how it performs.