Since my engine is tilted forward I must add extra vent lines from intake.
1. Front of radiator house
2. Not used 3. Vent line with AN4
4. Impossible to use because of headers
5. Sender to Water temperature.
Will this work or sould I add extra vent line from 2,3 or 5 ?
Yes, sort of like this, center of T goes to header tank: Or run two separate hoses back to the header tank. Your choice. Set intake gasket on head, figure out where hole would be best suited, transfer to manifold and confirm best location and drill piolet hole, then tap drill size and tap for fitting.
Only open up gasket to suit hole, do not cut out to suit entire water port. You need gasket area near edge to seal it. The water port in head is so that it can be used on both sides of engine at front.
I added a third line from #2 to header tank. You could tie all three points together and run a single hose back to header tank and it will work the same way. Keep hoses small, AN4 or AN3. You are trying to pass air not high volumes of coolant.
Anywhere between the water pump and thermostat is going to be high pressure, whatever you use is going to act as a bypass. You want nothing bigger then .060, and preferably smaller if you can do it, just to let air pass and then whatever water can fit through the smallest portal. You can thread a plug into the fitting and redrill, that works good.