Well, I'd probably start by checking the oil-pump out. Broken teeth, excessive wear or debris can shear that pin easily.
A screwed pump would also give you the vibrations.
Short of that, pull the camshaft and check the gears and the bearings.
I honestly can't think of how worn cam bearings would break the pins, but if it's not the oil pump then we're just going to have to eliminate everything else.
A worn cam bearing or damaged distributor gear could give you your vibrations though...