He can put a temporary gauge at any location on the pressure side of filter. That is the top hose. You can tee it at the filter or down below as in pic. You can just plumb it with fittings, don't need tubing. He is right you won't get pressure until it starts running. Monitor right away, above 10 psi and climbing with revs. That will be later when timing is sorted. Just wanted to know if you did that yet.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn