Can't respond to tightening a vbelt for the cutter wheel belt. Not sure why you converted. I've got over 3000 hours on my 252 with factory setup. Last cutter wheel belt got over 800 hours. Belts are about $35 bucks, what's not to like???
The only time I started going through belts is when the upper sheave, the smaller one, was worn real bad, that was about at 1800 hours. The problem is that the inner ribs get worn down and don't grip the belt. So you have to check to see if they are the same height as the two outer (thicker) edges of the sheave, or pulley. Just place a straightedge and check. If they're much below the outer ones replace it, about $75 if I remember right.
Important thing about tensioning the belt is alignment of upper and lower sheaves, or pulleys. Place a long straightedge, I use the belt cover plate along the sides of the two sheaves and see if they are flat against the straightedge, if not adjust their position on the shaft(s) to line them up. Also make sure the jackshaft is parallel to the cutter shaft. I just make sure the jackshaft is square to the boom it's mounted on, or check the space in the slot for the mounting bolts, make sure each side has same gap.
Belt tension I do by hand. Tighten so that you feel some resistance when turning the wheel by hand. Take it out and grind. If belt squeals at all adjust perhaps a 1/2 turn, that's all. You'll find the best tension for the belt is just beyond the slipping/squealing point. Easiest on the bearings too. Adjusting the belt is so simple that it can be done in less than 5 minutes. Don't bother taking off the cover and such, just loosen the jackshaft bearing bolts, one side is all that's needed, turn 1/2 turn on adjustment bolt, tighten back up. Once a new belt is installed and broken in I adjust belt about every 50 hours, that's it, so simple.
Same principle could be followed with the vbelts you installed. Have fun!
Stumper63