My cow this year (mature cow, probably the size of most young bulls) weighed 195 lbs. That was whole legs above the hocks, and the loose meat except for the back strap and tenderlion. The loose meat took up about 1/2 of a 5 gallon bucket, hanging next to the quarters. I figure the backstraps and tenderloins were about 15 lbs total. If I had help, and more time, I think I could have gotten a little more meat off of the carcass, and had I made a better shot, I would have had about 4 lbs more in the back straps.
So
210 - 30 (loose meat and tenderloins)
180 split 60/40 is 108/72 or 54 and 36 lbs for the front and rear legs. I left the lower legs on while carrying it out for easier handling at camp. I figure the 60/40 split is a pretty good estimate of the weights.