proper temp sensor wire routing

[K25alive]

What is the proper routing for the green wire from the temperature sending unit to the temp gauge? Right now my wire runs parallel to the block, then at the last spark plug ducks left in between the block and the exhaust manifold and appears to keep going south, I lose track of it. Is this routing correct? It doesn't seem logical it would pass in between the block and the exhaust manifold. Maybe this is why the gauge doesn't read correctly, the wire has been compromised? The truck is a 1979 K25 with 350ci.