Hi Micke,
I know the big v twins with the external plates bolted to the cast in rocker pillars are referreed to as "dog ear"
But I would have always considered the engine in the linked pic as a dog ear,
Anyway what I wrote earlier still stands, mucho £,$,€, SEK !!!
That is the type of engine for sale in the link I gave you, (not sure id single port?)
I have not seen another one for sale in 30 years!!!
Some years ago I found such a head and remembered that there was someone on this forum looking for one
I put it with the rest of an early 30's 350 engine and sold it to the advertiser
You need to source a lot more parts for the project bike, do not get hung up on finding the engine parts, but work with what you have and get the bike completed, blank off the left exhaust port if you only want to fit a single pipe.
There is no point is chasing an image in a photo of someone else's bike, without strong proof how do you know what was supplied 90 years ago
Catalogs were only a guide, production by small manufacturers (especially)varied quite a lot from the catalog images
John