I just watched the included video. The spacer you mention is to have a 'backstop' for the inner bearing to compress and align the rotor with the center of the caliper so the pads will wear even, although it is a floating caliper, it can only move so far. The missing or in place spacer should not damage any linkage, but it may cause a tire rub because it moves the tire out. Most important, the ring not being in place will cause the spindle to seat the inner bearing. Look for wear at those surfaces.
The old bearings should have a PN on the edge of the race. That will lead you to new parts.
1968, hardtop, 289, C4, seafoam green.
1966, hardtop, 289, original 3 speed, on the road and fun to drive.
1968, hardtop, 200, 3 speed, in work.