While I think that around 20" is the OPTIMUM .22 Mag length, I am sure that you would not notice any difference in terminal performance if you used a 26" barrel. So I would say that you should get the rifle you like, regardless of barrel length.
I can say that in both my 20" barreled Winchester 9422M and Ruger 77/22M rifles that 40-gr Win Super-X JHPs are deadly on big jackrabbits as far away as you can hit them.
