I had a lot of dealings with the vintage guys down in Spain during the 1980s.
There is quite a resevoir of old bikes down there but lots have been heavily modified,often ingeniously, as Franco stopped all imports.
The Spanish army used ohv nortons, and officers issued with ohc Velos.
pre Franco Spain was quite big market for British bikes.
that Norton type plunger set up was an after market thing .I have seen some brilliant engineering out there to keep stuff on the road, and some a balcksmith would be embarrassed by.
Last time I was out there I me a guy making cam followers for OHV Nortons, and a Lucas type magneto entirely made from scratch.
Some really class bikes out there, I have seen three OHC Matchless from the 1920s; G45, mk 8 KTT Velo, Manx, Inter, 7R and a chopperised OHC Ariel 4!!! I personally sent out some very good bikes, and once used to cut the rear fork ends off old 16H frames to replace those plunger conversions.