Hmm... have you tried operating the 3 point hitch yet? Possibly with any load on it? Unless I'm missing something, the valve "tank" connection you hooked to the 3PH (at the block) only has flow available when the remote valve is operating and oil is being returned from a cylinder or motor. In other words, you're using "second-hand" oil flow to operate your 3PH. I think you do need a different valve, one with 5 connections, those being "pressure in", "tank", "power beyond" (usually with an adapter) and the 2 work ports.
This is because the oil being returned from the cylinder or motor needs somewhere to go when the cylinder or motor is being operated. In this case, you have it flowing to the 3 point hitch instead of the tank. What I THINK will happen is that once the accessory cylinder is at it's maximum stroke (either extended or retracted), is that the 3 point hitch will stop lifting, since there's no more flow to it at that point. There's also the issue of back pressure on the remote valve. If you have a load on the 3PH and the valve calling for more oil, that load pressure will be felt at the tank port as well, and may bind the remote valve.
I hope I'm wrong, but I don't think so.
The way the power beyond system works, is that it is a series circuit in which the items that are first in the flow path take priority over those that come after them. 95% of these are plumbed with the loader coming first, the remote valves second, and the 3PH coming third in line. The 3PH is almost always the last item in line. When you're using the loader, if you're using all the oil flow (i.e. the valve is fully open), there is no oil flow to the remotes or the 3 PH. Same with the remote.. if it's fully opened there is no flow to the 3PH valve. This can be a problem if you're using a hydraulic motor to drive a spreader for example and want to raise the 3 PH while the spreader is running. I think a flow divider would work in that instance, but we're getting beyond where we need to be.
I've added some more pictures of my valve hookup. Just in case. From what I can see, Gordon's is virtually identical to mine.
Sean