Wrencher88, it was fairly common to add a tee to the oil gauge fitting and run a copper line to the 1/8" NPT fitting at the top of the head on the passenger side between #3 and #4 cylinders. That hole normally has a plug in it, but the plug can be pulled to have an auxiliary oil line to the rockers.
If you look on eBay, you can probably find a kit for the auxiliary oil line.
Sometimes the line to head that runs inside the block (newer engines) or through the oil feed tube inside the pushrod cover (older engines) gets blocked. The auxiliary oil line is a way to get oil to the rockers if the primary line is blocked.
Crimping the oil feed tube was commonly done to force more oil through the rockers instead of allowing some oil to bypass the rockers to the return loop. Crimping it forced all oil through the rockers. Crimping the line was VERY common. Chevy changed to a crimped design from the factory in 1959. Drilling a hole into crimped fitting sort of defeats the purpose of crimping it, so I'm not sure why someone would have done that.
Matt
