OK, thanks for the info, had not read the other thread, nor did I go searching
Here's a few quick observation from the Reg manufacturers install sheet
Return Line Backpressure: Even when the recommended return line size is used, it is important to check the backpressure in the return line. Once the pump and regulator are installed and all the lines are connected, check the backpressure in this manner:
~Remove the jam nut and pressure adjustment set screw.
~With the engine off (not running) turn on the electric fuel pump. Let the pump run until the lines are full of fuel.
~With the pump still running, check the fuel pressure gauge. It should read no more than 3 psi (less is better).
~If the gauge reads more than 3 psi, the restriction in the return line is too high.
~If the restriction is too high, reduce the restriction with larger lines, fewer sharp bends, etc.
This is definitely worth checking, by the looks of it you may have a short 90 (or 130 ?) out of the reg for the return line, a quick check will show if back pressure is an issue (even though you have a -10 return)
Regulator Mounting: The regulator should be mounted within three feet of the carburetor. In general, closer is better, however mounting the regulator directly to the engine is NOT highly recommended due to the vibrations and high temperatures. As the regulator heats up the fuel pressure will drop slightly (usually about ½ psi). If the regulator is mounted directly to the engine, the extra heat may lower the pressure 1 psi or more.
Cant see it being a real issue, but it is mentioned on their sheet. Stranger things have happened
Are you running a good relay for the pump, and has everything been checked out there, wiring etc. Possibly check the grounds, some of the pressure issues look G related (more variation in lower gears) and bad grounds are easily affected by this.
I must say I personally prefer the BG style of bypass setup, where the carbs get the full flow of the pump FIRST, then any residual is sent back to the tank via they bypass reg. Very forgiving, quick to react and nothing has to go "through" a reg, to get to the carb as in this case, less plumbing as well.
This way the fuel doesn't have to make its way "past" the large brass ? bypass plunger to get to the carb (pic of bypass plunger attached) Assume yours is similar to that pictured below from install sheet ?
And carb setup ?