The K7 sprocket carrier mounts the rear sprocket 10mm outboard, to match the 10mm offset in the front. A pre-K7 carrier can be installed on the K7 rear wheel to correct the alignment, or an offset front sprocket can be installed on the early engine with the K7 rear sprocket carrier. Six of one, half a dozen of the other.
If the alignment is off, there may be more wear on one side of the rear sprocket than the other.
To check if the chain is 530 or 630, measure the center-to-center distance of the pins in the chain: a 530 chain has the pins 5/8" apart, while a 630 chain has 6/8", or 3/4" apart.