Water temperature sensor

I'm fitting a new water temperature sensor gauge complete with its capilliary tube.
What is the recommended routing for this tube between the cylinder head and the grommet in the firewall?
The previous sensor tube ran across from the cylinder head to the underside wing edge and then along this edge but dangerously close to the fuse box and live terminals.
Is this the recommended route or do I take it straight to the grommet and if so what do I do with excess length of tube?
Should one insulate the tube past the fuse box? If so, what with as the tube obviously gets quite hot.
Any advice?
Photos would help

Hi Andy,

My 66 has the tube running alongside the head. There is a small P clip under the heater valve that holds it.
Between the engine and body there are a couple of loops, about 2 - 3" diameter, to allow movement between engine and body, so as to not break or fatigue the tube.

Herb