Small update.
Sold my old 1641 en built a 1776 out of 90% NOS VW parts the carburettor is a 37mm, stock cam, stock crank and stock heads with a CR of 1:8.3, also using the flaps and thermostat, engine warms up much quicker now, didn't had them in my 1641, took ages to warm up.
Dog house cooler...