Mark, I'll just toss in some thoughts.
First, the 3 point vacs were never made for the RH discharge tractors. This will need to be a fabrication route. I recommend you DO NOT alter the original mounting framework as you go in to this undertaking. Unbolt the motor/vac housing from the framework, then start with just the power head and new metal. Save the original mounting system completely ... it would not be much use in new fabrication (IMHO) and could be quite handy later when you sell or want to change back.
Second, a hydrabagger ... not a trailer vac ... gets VERY heavy on the back end of the tractor. I think your HH34 3 point hitch would be strong enough to carry this, but make sure the fabricated frame is strong enough to react the 3 point if you accidentally try to move it. Even with the framework mounted up as closely as possible to the tractor, it will absolutely make the front end light when the bags are full. You will likely want some counterweight accommodations.
Third, the duct geometry coming up to the vac is just about ideal in the OEM framework. The duct clears the tire, but doesn't sag, etc. It is actually more well developed than one might imagine. The original 3 point (B98-3) and trailer units had the vac inlet more parallel (not quite though) to the axle, with a rather long inlet snout. Personally I have never liked the way those carried the hose.
Finally, if you put the 3 point hitch on quick connect hydraulic fittings, you will find it takes not 5 minutes to R&R the hitch. Then maybe another 15 to R&R the vac unit, including the ducts and baffle inside the deck. It will take 10 if you are mounting it to the 3 point. R&R of the hitch is my chosen route ... though I will admit that using either a RM48 with mulching kit or the RM60, I don't often use the vacuum any more. I used it routinely until I found those 2 options.
Best of luck with the idea and project if you take it on.