I have a 1906 scanned map that I am trying to georeference in QGIS for Mac. The map has French and English lat-long, indicating them as either "Meridiano de Greenwich" or "Meridiano de Paris." I would like to know what the closest approximation to "Meridiano de Greenwich" for choosing the CRS might be.
My Spanish (Portuguese?) is rusty but I'm going to guess that it refers to the Greenwich Meridian, so your map is probably in some form of Lat/Long with 0 degrees at Greenwich so try EPSG:4326 first.
To really determine the projection we'd need more details than just the prime meridian.
Second try, with EPSG:4326 and the following GCP:
mapX,mapY,pixelX,pixelY,enable -74,20.1666666666700003,2053.94253295474391052,-2419.17835250553116566,1 -73,20,5225.22388495872564818,-2983.42925651106543228,1 -72,20,8392.67980710504343733,-2983.42925651106588703,1 -71,20,11579.26287853968642594,-2991.08011622639514826,1 -70,20,14754.36966040133665956,-2991.08011622639514826,1 -69,20.1666666666700003,17933.30187212064629421,-2421.09106743436450415,1 -71,18,11590.73916811267554294,-9723.83666571615322027,1
works reasonably well, compared to Natural Earths world boundaries:
You can improve the result by cutting the map along the foldings. But take in mind that surveying on Haiti was rather basic those days.