You could try sourcing a double acting spool valve, off a tractor, for your direction control.
They are not over cheap, used, on E bay, and a mental price new.
Some old yokel has probably got one rotting a way on a tractor that got pushed under a hedge 15 years ago. Finding the right yokel is the challenge.
Hydraulic hoses are not over priced, especially the sort of size your looking for.
Agricultural workshop type places often make them up to measure.
So do some plant hire firms.
One of the local tyre places used to round here, for example.
I'd be considering buying that scythe, if I hadn't knifed my fridge to death last week, trying to defrost it. I could find work for it.
Only so many pennies in the piggybank.
Oh yeah, and my mower is a 21 inch cut Viking. Every week, I follow it around gardens for hours and hours and hours............