Thank you for all the input everyone. Its keeping me motivated to get this M on the road. The cylinders were leak down tested and inspected with a borescope before the cylinder head was removed. Everything came back within spec and although the valves weren't seating perfectly due to carbon buildup there was no evidence of valve clash due to the seized intake camshaft. I know the s55 is an interference motor but maybe its only the exhaust valves that strike the piston in the event of a failure?
All the crank hub failures I've seen seem to have exhaust valve strike.