I feel that Norvil may have moved the top gearbox bolt hole slightly forward to help fit/clear the starter motor around the rear iso mount. Maybe? As the one supplied in the kit is a copy of the MK3 cradle I wouldn't know for sure. The starter is tight for clearance back against the iso. This would explain the loose belt. I used a 32T front pulley belt system on this matching# bike for 20 years with great reliability, the Norvil kit supplied a 33tooth pulley and I eventually made up a 34tooth pully to achieve correct belt tension.