Hello !
Type, size and construction of the bulb can atter depending on the construction design of the enlarger.
As you use an enlarger with condensers, you should have a bulb large enough to light the top condenser totally and of enough power to get a decent light level on the baseboard.
Try to measure the evenness of the lighting on the baseboard to check if the bulb is large enough to cover the top condenser : put a grade 5 paper on the baseboard, and to a test strip in order to get a pale grey on the center spot of the baseboard.
Then expose a full sheet (the largest the better) at the same setting. As it is a grade 5 paper, any light ouptut variation will show.
So you'll know.
Often you can adjust the relative position of the glass of the bulb regarding the condensers. It is not clearly described in the user manual but...
My Durst enlarger was designed for 4" dia bulbs which are no longer made. In order to even the light on the baseboard, I am forced to use a very powerfull lamp and a frosted glass betwenn the bulb and condenser. I have less than a 1/3 stop difference between the center and the corners of the baseboad....