I experienced too short (for me) exposure times when I was printing 6x7 negatives with a Beseler 23XLII. Can't remember what bulb wattage I was using, but my solution was to add a neutral density filter to the filter drawer, in combination with variable contrast filters. It worked for me.

Now I am printing 4x5 with a Beseler 45VXL and a 250 watt bulb. Exposure times are admittedly short, but in the acceptable range for me. If I start doing much dodging or burning (I do straight prints only right now), I see a need to lengthen exposure. I would do this with either a lower wattage bulb, or by adding neutral density filtration.