On some things I can find incredibly detailed information: the name of the son of the landowner in whose property the rebels from Minas Gerais stayed overnight, the hill they pointed their artillery at (findable on Google), and the hour and name of the gas station on which the commander of the legalist troops had a phone call which changed his heart. The station can't be found, though. Some battalion histories list the exact address of their former regiment's HQ. For finding military units I'm combing through:
-Decrees, which have a lot of information on unit establishment/disbandment/reassignment all the way back to the 19th century, but a lot of that happens through ministerial documents. They may also be available online but I have yet to dig for that.
-A document listing where the destination of unit archives. Some ancient ones with remote deployments are simply listed as "not located". What's more important to me is that the unit existed. Also curious are the archives of paper or rapidly disbanded formations such as the 14th Infantry and 2nd and 3rd Expeditionary Infantry (the 1st was the one in Italy) divisions. However some potentially relevant caçadores battalions existed but searching their name reveals nothing.
-A lengthy thesis on the army's reorganization in the late 60s and 70s. It lists divisions and brigades in 1960 and describes what took place once the regiments were disbanded and their battalions distributed to newly-formed brigades. Also mentions how far away the regiments were from their paper strength and armament, some only had a single battalion. Now that I've looked at it again, it has a real order of battle in 1960 down to the battalion level! I think I've hit the jackpot. Further, the sources might be very helpful if I need further research, but a great number of them are probably unavailable online.
Now I already see I missed a caçadores battalion in the Planalto Military Command, the 10th in Brasília.