A quick update on the replacement of the dipstick on my 1700cc Type 4 engine. The old dipstick was missing its top seal, so oil was seeping out when driving. I got a dipstick from a Type 25 from NewtoVW and modified it as follows.
Dipstick marked up at the slightly higher level of newer Type 4 engines (Ratwell has comparison pictures http://www.ratwell.com/dotmac/Sites/Parts/PhotoAlbum83.html).
The seal is to big for the tube on the Type 4 engine so I pared it down using the serated blade on this knife to give a reasonably 'round' finish.
Still leaking a bit between the end seal and the stick, seems to be a bit of pressure in the crank case so I'll take off the breather box and check that out.