No direct experience with the 755, but I ran a 4' Woods M4 brush cutter behind my old Deere 855 MFWD, for mowing trails, and that worked great. The 855 was rated 23 hp engine / 19 hp PTO, if I recall correctly.
Even the 855 was a little light in the nose when I'd remove the loader, so it'd want to pop wheelies going up hill with that small but heavy 4' brush cutter. Wasn't a huge problem, I kept the brush cutter low (or down) when going up hills, to avoid the issue.
Note that the belly mower lift is the 3-point control, but you can lock the mower in the up position, using the height control wheel, when you need to use the 3-point without removing the belly mower deck.