Mystery - Strong Fuel Smell

1. Fuel filter should not be horizontal, it should be vertical or max 45°. See right-hand column of this.

2. Metal fuel line running right above head and hot exhaust manifold or header = this problem you're having. Do the Fuel line mod and fix this and the fuel filter orientation at the same time.

3. No heat shield under your carburetor. Put one.

4. 160° water temp on highway means your engine is not reaching operating temperature. Put the correct 180° thermostat back in it, see here.