You may want to experiment with 1st gear starts using the "shift down to 2nd at a stop" method before converting your transmission.

When I first got my 260e I wanted to convert it but after trying 1st gear I changed my mind. 1st seems to be a very low gear considering the rear axle ratio, and the car lurches and shifts hard into second. In everyday traffic this could get really irritating. I understand now why the cars is set up to start in second gear.