Does Gilman have an archives? I'm pretty sure St. Paul's and BL do, and Loyola should have one as well.
If those 4 schools and McDonogh all have decently complete archives, you could probably pull together a pretty complete history of the MSA, at least as far as it comes to schedules and championships.
It's a shame record keeping was so bad because some of these schools would probably be near the top of the national lists for most wins in several sports with as long as they have been playing. McD football goes back to the 1880s and baseball back to the 1870s, and I'm sure City and Poly both started playing those sports around the same time.