I had a 74 R90/6 for a couple of years and it was a pure you to drive and together with that massive torque at hand you needn´t change gear that often! It had a single disc brake, sorry to say, so braking wasn´t that good as yours but it worked fine. Speed was not the thing but around 70-100 km/h it performed best in my opinion, especially on small Swedish countryside roads with little to no traffic...