The line and gauge are (eventually) full of oil. So you need to make sure the connection at the gauge doesn't leak or you'll get oil on your shoes. New fittings and ferrules would be a good thing.
Get enough line to put a coil (3-4 inches in diameter and about 2 full coils) in it just outside the firewall. The main purpose of that coil is to give the line flexibility from vibration between engine and firewall (as well as act as a snubber to keep the gauge needle from bouncing too much.)
