In the photo your fuel pressure regulator (left side by cyl. 5/third one back) has no manifold vacuum to it. Looks like it's plugged with a rubber cap or kinked line. Can't see where it should be attached to manifold vacuum. No vacuum, no fuel pressure regulation. It's going to run full pressure with no vacuum. Which would explain constant 60 psi. That is unless my view is obstructed. This is the vacuum line I mentioned earlier that can leak fuel and dump raw fuel into intake. Remove vacuum line while running and make sure no fuel is coming out of the vacuum port. It may only leak with vacuum applied. Typically will be wet with fuel when you remove vacuum line. You can pull vacuum on it with at tool and clear hose to check for fuel leak. Also make sure it's attached to manifold vacuum when you done checking it out. You stated your regulator is 1/2 way between tank and engine? The tank pump supplies the max. pressure and flow and dumps extra fuel back to tank via filter. The regulator on the rail controls the pressure at the injectors. You want instant ramp of pressure at injector rail when throttle opens to offset loss of intake vacuum that helps draw fuel thru injectors. Combined rail pressure and vacuum at the injector tip inside intake control fuel flow thru injector. If regulator vacuum port is plugged off, plugged, or has no vacuum to it, it would over-fuel the injectors with no pressure control at idle. This appears to be a return-less fuel system meaning the fuel is returned to the tank from the filter in the back / 50% back to the tank that you mentioned. This keeps fuel cooler instead of flowing it to hot engine compartment and back to tank. Let us know what you find.