Well I never researched much on the 1g on how to run wires/hoses/tubing through the firewall into the engine bay.

On three cars 1g,1g,2g I did the following...
Boost gauge on the 1g I cut a hole on the steering rack boot and ran the hose through there.
On my current 1g I tried running the Water Temp. gauge tubing through where my shifter cables were but that eventually got pinched, so I cut a hole on the steering rack boot and ran the tubing through there.
On the 2g I did the same thing I posted for the 1st 1g.

This might have been somewhere but thats what small trick I learned inorder to get something to read in and out from the engine bay area. Might be ghetto but hey it works and you can't see any of it