I don't think that spec sheet gives the answer. It shows the flow difference for the two tractors, but flow does not translate to force. What you want to compare is pressure. It is the system pressure fed to the cylinders that determines the force developed (assume same diameter piston in the cylinder, which is the case if you are comparing the specs for the same loader on two different tractors).
But in the loader spec (see:
https://kubota.ca/getmedia/87f3e907-c4f5-400e-95e0-f7b00047bbaf/L60-CAB-ENG?ext=.pdf) I see what you are getting at. I think the key to answering your question is in second to the last line in the loader spec. It shows a different relief valve pressure between the L3560 and the L4060 of about 70 psi. It is a relatively small difference. A rough order of magnitude of the difference would be a ratio of the two pressures (2560/2630 = 0.97). Which means the cylinder force you can get out of the L3560 is 97% of what you can get out of the L4060. Seems pretty insignificant to me. There may be some multiplier due to leverage attained by the loader design... but , that would be applied to both and still seem pretty insignificant. The LA805 is still going to be better and have more force capability than the LA555.
Now speed is another story. The flow is what determines how fast the cylinder will retract or extend. The flow available for implements on the L3560 HST is 8.1 GPM, and the flow on the L4060 HST is 9.4 GPM. So the L3560 HST has about the same force, but will operate 86% of the speed of the L4060 (8.1 GPM / 9.4 GPM = 0.86). Probably just noticeable, but not that significant.