That Gresen valve does not appear to have a power beyond port, just the low pressure return (tee'd) to the reservoir port. The power beyond feature allows flow to pass through the valve with pressure under control of the built in pressure control valve and on to the backhoe control valve or other auxilliary valve.

Problem appears to be your system is backwards with the blade control pressure being lower than the backhoe pressure and there is no power beyond feature to the hoe valve. Again it appears the diverter/selector valve is about all you can do and that just eliminates the manual hose connecting. Yes, an even more basic appraoch would be a couple of manual valves.

When all the "prototyping" is done.
Do me a favor and replumb all of the hoses (except any low pressure returns to the tank) with wire braid pressure rated hose. Water pipe fittings I see in the photo's are only rated at 150 working pressure.
Before you all slam on me for that comment.
Tear apart the hydraulic systems on your old CATs and look at the original pipe fittings used, you will see they are twice as thick as your hardware store variety.
Jeff

For a open center hydraulic system I don't see anything wrong with your hose and piping. The water pipe fittings, low pressure hose and hose clamp is on the low pressure return to reservoir and is quite typical but usually run through a return line filter which I don't see.

"drujinin" wrote:

When all the "prototyping" is done.
Do me a favor and replumb all of the hoses (except any low pressure returns to the tank) with wire braid pressure rated hose. Water pipe fittings I see in the photo's are only rated at 150 working pressure.
Before you all slam on me for that comment.
Tear apart the hydraulic systems on your old CATs and look at the original pipe fittings used, you will see they are twice as thick as your hardware store variety.
Jeff

Yes, but the new ones are chinese so they must be better.