Filters for a B-22
I have two enlargers in my darkroom, a B-22XL (longer girder), and an Omega D-6. As I am now using Kentmere and Ilford papers almost exclusively, I have two sets of Ilford filters, a 6-inch set for the D-6, and an under-the-lens 3-inch set for the B-22. I also have two sets of Kodak Polymax/Polycontrast filters, (the same configurations as the Ilford filters; now retired and headed for eBay), as well as a set of AGFA filters, which have been cut to fit the filter drawer of the B-22.
I find it much easier to deal with the under-the-lens 3-inch set for the B-22 when using up my last few boxes of AGFA paper (insert a heartfelt sight >HERE<), rather than juggling cut filters in and out of the drawer. Also, as I often employ split filter printing methods, sliding a under-the-lens filter out and an other one in, or the same procedure for the D-6 with the 6-inch set, is much easier that running the risk of bumping the B-22's head when changing filters in the filter drawer.
My B-22 leaks light like a sieve, especially as I use a home made glass negative carrier with it. So, I have blocked the light leaks on both of my enlargers with old black socks, wrapped around the appropriate place on the enlarger, and held in place with an ordinary wood clothespin. Moving one of those to get at the filter drawer will almost always disturb the head, so I stick with the under-the-lens set for the B-22.
(One of my photographer friends saw this arrangement recently, and thought that I had a screw loose; I told him that my enlarger gets cold in the winter, and the socks help keep it warm!)
As for the actual filters themselves, I recently borrowed a friend's densitometer to make some sensitometric tests on several B&W papers, and part of the data I gathered was a reading of all of my B&W filters. I don't have the data in front of me at this moment, but I did find that both sets of Ilford filters were pretty much identical with each other (both #2's were the same, et cetera), and found much the same with the Kodak filters. The three sets (Ilford, Kodak and AGFA) were different from each other, but all tended to "go" in the same direction; that is to say, the higher the contrast number, the higher the magenta-yellow density ratio.
So, my suggestion would be to use a set of under-the-lens 3-inch filters for your enlarger. The purists may say that they will degrade the image quality, but for the prints I make, which are 11x14 and smaller, I have never noticed it. Also, if you get a second enlarger, you can move filters between the two enlargers without any problem.
If you are interested in the filter data, drop me a PM.