Handy References: On Bench
#1) Delco Service Bulletin 1R-262/263 (dtd 4-1-66)
Handy References: On Car
#2) Chevrolet Chassis Service Manual Section 6Y "Charging Systems"
I have never Bench tested a VR.
If it is an option (Dated component) I used to send it to Pirkle for cosmetic and functional restoration, And a few have hidden a modern WELLS 715(?) electronic reg under a delco cap and housing.