My gear drive Mitsubishi is rated at 19 HP (PTO would be less) and I use a 60" blower.
Yes high rev is too fast and low rev is kinda slow but OK in 10" accumulations but terrible in say. 16 and up.
You will develop tricks to use your blower.
Take half wide 'bites'.
Raise the blower perhaps 3" for the 1st pass and re do that pass followed by 'half bites' at each side.
Really small snow falls (like couple of inches) you can use H R .
Big main trick is keep up the RPM's.
Also it you have dual or 3 ranges of PRO rpm's try the middle range (mine is 650 RPM) and that is my best performing PTO speed and have used it for 6 yrs without any ill effects. Also it allows you to use less engine RPM's and still get good blowing results.
I actually blow thru the 3 ft city plow dumpings with raised blower and then take small bites for the following passes and that stuff is heavy dense snow.
Buy a set of chains and add some weight up front and you should be able to adapt easily.
And suggest chains be at every 3rd link, also turfs take chains wery well, in fact better than R4 or R1's.
PS, that is a nice blower U have, I'd trade mine for it in a flash!
(and I'm not that far north of you, (Montreal))