You can get a 25.4 m/c from a VW T4 which is a direct fit servo wise. there is a 2 port version and 4 port version. the 2 port needs the reservior modifying as the outlets are on the opposite side to the standard 306 one. i have just fitted the 4 port one as the reservoir fits without any issue and blanked off one side with M10 plugs.
4 port: https://www.vwheritage.com/shop/7D061101...-01-96-03/
2 port: https://www.vwheritage.com/shop/7D061101...-01-99-03/
be careful with the 2 port one though as the one i ordered required M12 fittings not the M10 stated.
4 port: https://www.vwheritage.com/shop/7D061101...-01-96-03/
2 port: https://www.vwheritage.com/shop/7D061101...-01-99-03/
be careful with the 2 port one though as the one i ordered required M12 fittings not the M10 stated.