Easy Guys. Yes, Brandis' Crank looks to be the right one with 82 mm stroke. Centre of big end journal to crank axis represents half the stroke. Cut out on the crankpin side of the flywheel is the clincher.
Does the timing side bush need a change? Sure the new crank won't fit? If it does need a change, heat is your friend, plus a bit of a push or smack. Camping stove or domestic oven, even barby, heat up good and hot until a gob of spittle dances, and the old bush should make a dignified exit. Domestic oven risks cooking the gearbox mainshaft oilseal, but these usually need a change anyway. New bush in the freezer, hot case, drops back in. Clean the oilway from the oilpump to the back of the bush while the old bush is removed. This oilway has a ball valve to prevent oil drain down on standing, we call this wet sumping. Plenty on the forum about this valve and it's foibles.
Your crankcase may need slight modification to take a later bush, but I would expect this to be a minor detail, BSA always were reluctant to spend on radical solutions. Plenty on the web showing bushing type used in later cases, the basic castings you can bet stayed the same so very good chance that the crank is a straight swap for these early cases.
Despite its good looks, that crank needs the sludge trap plugs removing. You will sleep a whole lot better knowing all is in order. You might find something like this...
Swarfy.
