Doing some more bits and pieces, the play in the engine was from the swivel tube bushes. Getting some brass ones made up which should last longer. New stacks are made up, also designed some reed block stuffers. Took a few days and 7 versions to get them how I wanted but they're a really good fit.
Also cut down the air intakes on the cowling.
Going for 185/195/195 main jets to start with, playing it safe! Also drilled out the needle valve seats, they were 1.6mm now 1.8mm. Ordered a bigger fuel pump, from the Yamaha v6 two stroke.
Flowed the exhaust and sandwich plate, removed some restrictions from there. This does mean the engine isnt UIM legal any more but I don't mind. If I go to Coniston again it will likely just be for a performance certificate rather than a record. Would prefer to go for the worlds fastest thundercat.