It is a problem for pre ADR27, ADR27 or ADR27A,B,C etc as you have to comply with the emissions requirements for a VSIII/VT, which means standard EFI top end, ECU, memcal, cats etc etc. You have to use the whole VSIII/VT engine, complete with ULP fiuller neck etc. No mods, no cam change, no memcal change etc.