One question on solenoid valves in general. Can the valve be mounted on the subplate so it aligns with either the work ports or the through ports? Or can it only be mounted one direction?
To be perfectly correct they can only be mounted in one orientation (the pesky engineer thing again). That is to say only in one direction (like North-South vs East-West) and only one way in that direction.
There is a small pin on the bottom of the valve that sits into a hole on the subplate & the bolt mounting pattern is rectangular to prevent you from mounting it any way but one.
Another thing to point out, if you look at the pictures from Snowback that you linked earlier, he's using the W.R. Long kit and their subplate has ports on only two sides NOT one port per side like the subplate you have selected.
There's nothing inherently bad or wrong with what you have, I just wanted to make sure you noticed that not all subplates are created equal so to speak and that you are going to have to account for that with your mounting position and hose routing. Trying to eliminate the gotchas.
As best I can tell W.R. Long is either making their own subplate or having it made just for them because I couldn't find anything like theirs after a couple good weeks of internet searches.
I did finally find one from Magnaloy that has ports on two sides but their design appears to be thicker (taller) that W.R. Long's and it's probably double the cost of the one you're looking at right now. That extra $$ buys a lot of 90 degree fittings LOL
Here's a link to a W.R. Long kit on a Kioti DK45 where they mounted the valve on the rear of the tractor (I never really liked that placement either but it's another good view of the valve & subplate and the port orientation)
http://www.tractorbynet.com/forums/kioti-owning-operating/331759-3rd-function-install-summary-dk40se.html
Oh and my one single best bit of advice - no matter how much help you get nor how much homework you do, something will still go wrong, you'll find something you could have done different / better after you're done.
Just take a deep breath and roll with it - it comes with building your own system.
