Hemikiller,

It is the first series of Fox "banjo-back" schneurle 40s and 45s from about 1973 or 1974. This one is a 40, as is visible on the mount lug. It is a lapped-piston, plain-bearing engine - the BB versions came a bit later... These ran well, and Fox developed them further over several years, up to and including the current 46 and 50 BB "big case" schneurles. The shiny, tumbled casting was the finishing method Fox used for all engines in that era. Later 40 and 45 BB Schenurles had a nicer light, satiny bead either blasted or tumbled finish.

Fox eventually offered an adapter spigot for the Perry carbs, but the adapter on yours does NOT look like the Fox item. There wasn't anything wrong with the stock Fox carbs, it's just that they were different to set up than the ST MAGs, Perry's and OS air-bleed types. A few guys who couldn't be bothered to learn how to set the Fox carbs gave them a bad rep. As I said, they weren't as 'even a caveman can do it' simple as the other types, but worth the effort when you did.

Provided the engine has lived on enough castor oil in the fuel, if it has been run much, it should run great and last until you're tired of looking at it.