I'd make a "sliding table" mitre fence for my table saw with some 1/2 plywood. Lay out the 67.5 degree angle on the plywood screw a cleat onto the lay outline on one end tight enough to hold the angle and make a couple of fine tuning test cuts then screw it down tight. Depending on the length this could also have a stop block applied and get your length cut at the same time. Nothing fancy but effective for the cost of some scrap wood.
EJ