The original one that William posted is my 12D Norwood built Z. That grommet even has a part number on it if you can blow the picture up enough to see it. From what I understand that isn't reproduced.
As far as I remember (been a while since I've been under the dash) that hole doesn't run into anything inside and comes out right at the bottom of the heater box (the added piece found on console cars). The Van Nuys examples that appear lower I think would be even better and would be right in the area where the front carpet is split as factory console cars had a 2 piece front carpet set.
Mine however wasn't hooked up, and the firewall had so much gook and grime on it, you couldn't see the grommet. The oil pressure gauge never worked and I had assumed it probably wasn't a factory gauge car, but I knew it was at least a factory console car. Wasn't till I started cleaning the firewall that the grommet appeared. I found remnants of the original line in the ash tray including the tall brass block fitting. I surmise the oil line busted at some point and sprayed the firewall with oil, which over the years turned into accumulated gunk an inch thick. Rather than fix it someone decided to just stick a pipe plug in the block.
