There are not too many options for VR
there are electro mechanical ones and electronic versions of the electro mechanical ones.
As for amperage, whichever one you buy will be fine. Originally the alternator was max output 35 (higher with AC or taxi/police)
The replacement alternators available today will most likely be in the 60 amp range.
So the VRs of today are designed to handle it.
Now for the $10,000 question....
Is your charging system stock for 68?
Post some photos of your VR and the back side of your alternator.