Ideally, you need a 3 spool control valve to replace the 2 spool, unless the valve has a spot for a 3rd spool blanked off (like my 440b did) - then it is just a matter of installing the spool and linkage. After looking at alternate ways of putting in a home-brewed set up, I ended up sourcing 90% of the parts from Bobcat. Prices were not outlandish.
Personally, I would get the aux's operating first before making any judgement on their speed. Small machines need attachments sized for their hydraulic flow. If I was to look at speeding them up, I would first start by running the pump slightly faster, before tearing up the entire hydraulic system.