Went out yesterday for a few hours and thought I would post some numbers.
1992 Sprint 286
1991 Evinrude 175XP
Air and Water temps were both in the low 60's. Just me with 1/2 tank of fuel and all my fishing tackle with the livewell empty I was able to top out at 62.6 GPS. Back in the summer when I was tournament fishing with my brother who is 300+ lbs. and all his gear with livewell full and full fuel we were running between 53-54 GPS.
By myself the prop will hook great and lift the hull but with my brother and his gear I just can't seem to get the lift.
6 inch jackplate may help that rig get close to 60 depending on health of engine and setup.....nothing wrong with what you got....The beauty of the 6 inch plate is you will not have to change steering cables or anything.