I don't know if there are any implications with the diameter of the tire/wheel (kinda doubt it).
A 530 sprocket (from K6 and prior) has a wider shoulder where it goes on the shaft relative to a 630 sprocket but the spline pattern is the same. Also, the 530 sprocket is held on with a retainer and two bolts. The 630 uses a big washer and center bolt (on K7s and K8s). I believe folks have done this (530 front sprocket in place of a 630) but understand that when doing this, the washer holds down the sprocket but does not make contact with the shaft (530 sprocket is wider at the base). On a 630 installation for a K7 or K8, you'll notice that the sprocket and shaft are flush... the washer makes contact with both of them when the bolt is tightened down. There may be 530 sprockets available that have a narrower shoulder at the base but I've not seen them.
As a related note: the original 530 setup on these bikes allowed the front sprocket to float a little (jiggle room on shaft... not mated firmly to shaft). The 630 did not. Realize you are "un-floating" a 530 sprocket and as I mentioned, folks here have done it with apparent success but the Honda engineers either changed their mind about whether sprockets needed to float or 530 sprockets (in their minds) should float.
The rear sprocket should be a direct swap.
530 on the left and 630 on the right.
