Richard at Lionheart have advised me that he has received the quotation from the factory for the 14mm locomotive wheel sets, which has an MOQ of 100 sets. Unfortunately he considers that this figure to be too high, together with the complicated and difficult assembly, so they shall not be offering this conversion.
For background I did I trial conversion for Richard of the standard wheels he supplied with 14mm axles and although the back-to-back was correct the flanges were quite fat so the wheels came out over gauge. Hence the need for special wheels with finer flanges.
I don't know if this decision can be changed with a firm commitment of numbers.
Regards
John