The stroke dimensions given in the manual or this thread might throw you off because Robart RB165 cylinders do not come in different lengths. The 165's are what you want.

In Europe Robart 165 rams come in 165S = short 165 = normal (what we use) and 165L = Long...

Set up right the Hawk (and not over built-I have seen Hawks 4lb heavier than mine because of "bling" added to the install) lands at the same speed as the UF

Dave