My 3-point backhoe (photo in sig) was specified for this tractor but even so, I've read that any 3-point hoe beats up the tractor more than a frame-mount version.
1350 engine rpm just sounds right for full backhoe power with smooth motions. My most common task is digging out stumps where I don't want to snap off lateral roots before I dig outward along them to free them so faster isn't necessarily better. I need to feel when the bucket encounters resistance.
If I know I can work fast and not run into obstacles then up to 1800 rpm but that's not common - and that requires more concentration to feather the end of the boom swing. Previous owner of this hoe said he tried using it a few hours and 'couldn't get the hang of it' so he never used it again. Where the roller chain for swing attaches to the chassis I found a fresh weld. I think he broke it the first time he used it. Several years now for me and no problems.
I occasionally shift the pto to its '1000 rpm output' gear, then run the engine around 1050 for very light work such as using the hoe to rip out blackberry jungle. This is essentially idling the engine, not working it. Actual rpm out the pto is still below 540 and the hoe has a decal specifying 'not over 650 rpm input' or something like that - faster than I would ever use.
Just choose what feels right. You don't need the engine's full rated pto rpm.