STM,
Good luck finding 100 pounders. I've got seven 35lb weights off an ariens machine on the front of my 2210. I don't have the JD extension bracket and don't know the total weight you can get from JD, but I really, really like the front weights I've got.
My kubota tiller is probably a little lighter than your KK, and the weight I have up front is fine for that. I've got a 4' JD rotary cutter, that even though I'm good with that too, I'm still probably 50lbs or so away from keeping the front end firmly planted under all conditions when using that.
For what it's worth.
Joe