If my experiences from half a year ago are still valid - don't. "Just" three ranks take a long time, and doing cargo missions (even if you choose the high rep option) isn't/wasn't the most effective way.I'm using my type 9 to grind to get the cutter. I am close, just three ranks away
Rank grinding worked better by doing passenger evac missions from Thargoid attack systems. Get a cold Phantom and the Thargs won't even notice you - and at least back then, a properly engineered Phantom could outrun the (inevitable) hyperdictors. If you want to stick to the T-9 and haven't done so yet (they also work great on the Cutter), I'd also suggest you unlock (at least) the Guardian shield reinforcements and FSD boosters.