Most hydraulic shops have restrictors, which are small inserts placed into the inside of a fitting, that have a specified hole drilled in them. The size of the hole determines the rate of flow. They are cheap, so get a couple of sizes to try. My older model 9300 John Deere industrial backhoe has restrictors in the swing and boom circuits, and the orifices are different for each circuit. Seems like they tried to fine tune it.
For a bit more money ($25-$50 per line) you can put manual flow control valves in each line so that you can adjust the rate of flow for different situations. Get the type that meters flow in one direction, and is full flow in the other direction. That way the valve for, say, cylinder extension, does not affect the flow for cylinder retraction; you can set a different speed for each function.