Bending the longerons is not something to dread. My solution was to take a hydraulic bottle jack (10-20 tons would do) and build a poor man's press using angle iron at the bottom and top connected with readi-rod and nuts. I clamped both longerons back to back, and made a hardwood "bending shoe" (with a slot in the middle for a close fit around the longeron flanges) to fit over the jack ram. At the upper end, the two cross bolts of the angle irons had pipe around them as spacers to these served as the other two contact points of the longerons. I used the full size drawing of the longeron curve to make an aluminum checking template. Using the hydraulic jack made it very easy to "creep up" on the amount of curvature without kinking or overbending. Yes you can print the PDF drawing out by taking it to a blueprint place, just be careful to check that the final scale is right.
Of more importance, and a PITA is the "sharp downward bend" that you have to put in the longerons to match the side skins on assembly to the front fuselage. This was where I reverted to the dead blow hammer suggested in Vans instructions. Each longeron was clamped individually to the bench, the initial bend/twist was put in by hand, but the final "sharp" part of the bend was with the dead blow hammer. It really took some hammering to get this profile right. Again, the top profile of the side skins is the guide here. If you don't get a sharp bend in the longeron, you may find the rivet pattern has insufficient edge clearance in the longeron flange, so it pays to keep checking this before calling it "good".