JD parts lets you search online with diagrams and part numbers. You can also cross reference a part number to see what other models use the same part. Like the loader valve is the same for 4010, 4100, 4110, 4115, 2210, 2320, 2520, 2720, 2305, 2023R, 2027R Also you can search those part numbers for online dealer pricing.
John Deere - Parts Catalog
That valve doesn't adapt very easy to a simple hosed PB plumbing set up to another valve so I would think you are somewhat limited with that. The block allows for outflow and return whether it there is another control valve (I have that setup for a hyd toplink and also controlled a dump trailer that way too) or just a full flow/return line out to something like log splitter with it own control valve. Just remember it cant dead head you always need an open loop flow back to tank. The JD PB kit does just that, the large hose shown in the kit loops the flow back when not in use with an open center valve.
If you go for those parts there is certainly enough experience here on TBN to get you through the installation. And there might be some blocks available if you ask because the old kits supplied an xtra one along with other pieces needed which can be had individually too. Curious to if can be done on 4010 and why the kit wasn't applied to that model
The cheapest and most simple way out would be some xtra hoses from the loader connects to the back there was once a special JD kit for doing just that too. But like you point out its one or the other... loader or rear hyd control.
These are some quick pics I just took of my xtra control valve setup with PB kit