Matt brings up a point that is really important especially for those of us who are not fluid techs. Gotta keep things simple. As Matt said it is an Open Center system so it makes sense to use OEM style Open Center Valves - which is why I got mine from Joe's Outdoor Power.
These are the ones I used for both my hydraulic blade project and for my splitter project. Simple single valves. Not what you may need for your loader unless it is a trip bucket.Cub Cadet 149 Tractor Hydraulic Control Valve
If the Henderson isn't a trip bucket, then a Dual Hydraulic Valve might be the way to go. Cub Cadet 982 1912 Tractor Dual Hydraulic Control Valve
The reason why I like these is because they are original IH equipment, not for a Cub but for the Cub Cadets. So it kinda keeps it real, at least to my mind. Being on a budget, I had to save my pennies where I could. I bought my 4 valves for $9.99 each ... prices has gone up a bit since then even though it has only been a couple years. The Duals have always been way more money.
Northern Tool has a Prince PRV available:Prince Adjustable Relief Valve — 1/2in., Model# RD-1850-H
I think 3/8" lines are more than sufficient considering the GPM of a Cub, but your Henderson might have 1/2" hoses. It might also be cheaper to redo the hoses as the larger sized fittings are more expensive but I wouldn't go below 3/8". Also, I use NPT fittings as well. The threads on these valves are 3/8" NPT but the standard opposing end is usually a JIC fitting. ORB and JIC are a bit more expensive. Tried to find some fittings at Northern Tool and Harbor Freight - but still seems like Princess Auto
is the best on line resource for looking up parts etc. -- Hydraulics
. I do have a neat collection of JIC fittings now though
There are many options out there but I guess it all depends on the state of one's budget.