An enormous amount of effort has already been put into Negro League research, so make sure, first,
that you're not spending time digging up stuff that's already been dug up.
The Complete Book of Baseball's Negro Leagues by John Holway
et al is regarded as the best, most thorough,
and most accurate of many books on the subject.
https://www.amazon.com/Complete-Book.../dp/0803820070
That's more than fifteen years old, though, and surely even more information has been unearthed since then.
A scholarly compendium of Negro League data entailing about 5,000 pages was in the works in recent years,
but we're unclear who was behind it or what its status is.
In any case, we'd strongly advise contacting the Negro Leagues Committee of SABR for guidance before you
do more work than might be necessary -- the specific information you want may already be available.