I know where to find a MB crankcase but not before March 2024.

I found a N.O.S deck for a 1954-59 single some years ago, Ben Hopman has it now.

L. Nesute

Advertised wrong it's 1929 only becouse the lifting grip is opposit the chainguardsupport remains. https://www.ebay.co.uk/itm/155581896972?hash=item243967590c%3Ag%3ASqAAAOSwy4pkdkqb&amdata=enc%3AAQAIAAAAwL08pvAw%2BexdwqCy57fAcWv9B5CjfZolwPS%2BUEbnLivb48d04wcVQGbauENRDe7ZWCBzl6BmRLJBvr188zy4lxPT5...

All good here andy.
The Imme also had a spare wheel next to the rearwheel, there was a Guzzi wich had one in front of the engine

The Imme is made like this not becouse the maker wanted to be modern or special, he just had only one size of tube.

Verkogd is like solt.

You have a prived message.

You will find the valve material pushed up to a ridge becouse the material of the new valves are not mathing with the guids, use an old valve and your problems are solved.

I don't see anything wrong.