I use a jig saw to finish the cut , but yes Jimmy's got it right.
I use a straight rafter as my pattern , screw on two 1/2 "x 2 1/2"x 6" plywood gauges on the top edge of the rafter one on each end, so they don't stick down more than 1"( use screws so as you mark and cut the gauges do not loosen )
I stack in , generally, 3 piles on the horses the "crowned " (all one way ) rafters as many as the horses will carry weight wise , spacing the piles so the pattern and guides can be ingauged on the top of each rafter pile.
Generally one guy on each end mark the top 3 , cut the top 3 , each person starts on a different pile pulling the one they are cutting to them . If you have help have the same person cut the same end they match what they do / did better each time so things are more consistant that way.
Nice job Jimmy
Bet it was a PITB climbing over / around those rafters walls etc to cut those rafters . A good set of horses would have made it easier , IMO.
Not a bad project to start a DIY build / project , angles , heigths , widths etc all practiced will build skills at least 3 ways .
Good luck , PEG