I have a 60" finish mower that I typically mow with in 1st Hi, sometimes 2nd Hi (I have gear drive) depending on the terrain and grass.
I also have a 4' brush cutter that will bog the tractor down in high tough weeds, but it could handle a 5' if you reduce the speed. The front end gets light if I take my loader off, so watch for that.
I use a 60" box blade and it has worked out real well and last I have a 72" rake.
Hope that helps, your
HST should have slightly less
PTO power but the
HST mow than makes up for that in versatility.