Sceptre Windshield gasket question

[erebus]

Sprucing up the windshield on my 1979 Sceptre and I know that the gasket that holds the glass in is TP-139 from Pompanette;
But has anyone replaced the gasket for the inside of the extrusion? The one that covers the wire chase for the wiper/nav light etc, and runs all the way around the inside?
Also anybody have a rough measurement for how many feet of TP-139 is required?
Boats wrapped and stored up here in the North East and don't really want to cut her open just yet for measurements.