Back in the day the bearing type chosen was the familiar NF type, rollers stay on the crank, outer case simply pulls off. These days the bearing type NJ offers an easier but slightly more expensive solution. Here the outer race, cage and rollers remain in the crankcase, the bare inner race stays on the crank.
The same problem of moving the inner race on and off remains, but access is easier with less chance of damage to a new bearing. I've had success starting it with a Stanley blade carefully hammered between race and crank, gentle heat and a succession of thicker wedges....old knives, chisels, ground wedge on a flat bar.
RD is on the money here. There is no sound reason why the race has to be a super tight fit on the crank. Assembled correctly the cush nut is holding everything tight against the crank. If you are an inner race sitting under some 65/75 ft/Lbs of torqued down cush nut, you ain't goin' nowhere.
In practice, and in unenlightened times many earlier owners would be unlikely to achieve this torque, with a drift and backyard coal hammer. Maybe this was a belt and braces design to ensure that at least there was some physical interference fit even with the cush nut looser than it should be. The split pin in the crank end serves more as a safety to prevent damage to the cases if the cush nut loosens, rather than a marker to say the correct torque has been achieved. Guilty as charged, m'lud. Thought it was tight when the hole appeared. I know better now.
Service sheet 208 recommends the nut is tightened "as securely as possible" tightening with a C spanner and Crank Float is allowed up to 0.005" Good enough, back then.
There is debate as to whether a simple deep groove ball race would do a better job on low stressed engines, as on the early Longstroke and early A50/65. No end float at all. Works OK on other contemporary designs. Bearing Type NUP offers a more expensive best of all worlds, outer race and rollers stay in the case but with no end float other than that present in manufacture, as the cush nut and drive sleeve tighten down.
Swarfy.