I think the real answer to the tug-of-war question would be an "AMA solution" ie you just keep moving the goalposts around until they end up over the 750cc sv Harley... The AMC clutch fitted to Matchless machines is the same one fitted to Nortons, used extensively for racing machines up to 750cc Norton sidecar motocross outfits and supercharged Triumph twins on grasstracks and sprinters, so I would say from experience of both that it's every bit as strong as the H-D unit, with the caveat that it doesn't have the sheer mass and won't stand sustained slipping in the way the H-D one will, partly because it's designed to run in an oilbath chaincase.
Do I know about 45s? A little... I've had several over the years and they are a lot of fun. That said, the cycle parts are hugely overweight and the gearbox is dreadful. When I started my current project I didn't look at those parts of the machine, just the engine. I've had a bike like this before and I know how much of an improvement axing 100lb or so and providing 4 speeds will make. It's a great shame the bike wasn't designed that way in the first place, as it so easily could have been.