Hydraulic pump ?s for mounting a Massey Ferg 220 Backhoe on my TD-6

My ? is this: I need a hydraulic pump with more power than the TD-6's engine mounted unit, and I don't know which would be best. I would like to use as much of the 34 hp that the TD-6 develops, if new, to run the backhoe pump. This means I need to optimise for the flow vs. pressure that the MF 220 Backhoe was designed for. I've come to understand that pressures where limited to 1500 psi or less on older hydraulic equipment, to which this certainly applies. However, all of its plumbing, o-ring connections, etc. and cylinders, look like stuff that would be rated for higher pressures. I'd love to know what psi and flow I should target the MF 220 for. I believe this backhoe was made primarily for the MF 200 crawler, does anyone know what its hydraulic pump specs were?

A this point, with what I know my solution is this: Given about one horse power required per 1 GPM flow at 1500 psi I think a Prince 21-spline 40 GPM 1000 RPM PTO pump would work perfectly but I am not sure. If I connect this pump through a PTO extension shaft (6-spline 1 3/8" female to 21-spline 1 3/8" male)connected to the TD-6 tranny's PTO output shaft which turns at about 850 RPM, the output of the 1000 RPM rated pump will decrease 15% to 34 GPM. At this flow I might be able to get 1500 psi. If I set the reliefs to 2000 psi or so, I am thinking that when I bog the hoe down, my engine will likewise bog, which will increase my torque, and therefore my psi will go up as my RPM and flow drops off. This will achieve good breakout force while having fast cycle times.

Does anyone know if I am thinking straight? Please inform.
And thank you very much, in advance.

My TD-6 is a late 1950s International crawler sitting at about 11500# with a 34 drawbar horsepower diesel. I also have an older extended track TD-6 in very good condition that I use for parts with the OEM Bucyrus-Erie Loader option. I got it because it's engine was toasted from rain in the muffler.

Does anyone know the weight of the MF 200 crawler? I am curious as to how my 11500# TD-6's balance will be with this backhoe.

I just found out that the MF 220 backhoe is a mid 1960s unit and rated for the low-mid 2000 psi range and flows of just over 20 GPM. This is preferable to a low psi unit to me but changes my plans somewhat.

The PTO shaft* of a TD-6 does run at 862 RPM as per their service book. Add-on pulley drives, 540 RPM PTO unit with a clutch, etc. changed the ratio to that needed with rear mounted gearboxes. The 862 RPM comes from the rotational speed of the upper transmission jack shaft.

* By PTO shaft, I mean the shaft that International provided to attach PTO accessories. It is a 6 spline 1 3/8" shaft located about 16" from the rear of the tractor's main bulkhead. It is above and in front of the main drive bevel gear and is accessed through a port on the rear buldhead of the tractor. My TD-6 came used, with only the extension shaft part of the factory 540 RPM PTO. Installed in my bulkhead is a 1 3/8" shaft which is female 6 spline where it connects to the tranny inside the bulkhead, and bearing supported male 10 spline, again 1 3/8", receased at the rear of my bulkhead. As I can find no 10 spline adapters I am replacing this part with a conventional, though modified, 6 spline female to male extension. This will allow for a tight, easily serviced pump mount safely above my rippers and below my fuel tank. That is if I can locate a pump that provides the flow/psi I want at 862 RPM.