"A chart" would be difficult. A free base accordion can have a convertor or can have 3 or 4 separate rows of free base. A convertor accordion can have 3 or 4 rows of free base. Free base can be C-griff mirrored from a C-griff button accordion, meaning the low notes are at the "top" of the instrument (in the playing orientation) or can be C-griff non-mirrored, with low notes at the bottom. The free base can be B-griff mirrored or non-mirrored. Finally the free base can also be a quint-convertor meaning it is the layout of the Stradella base and counterbase notes, first one and then two octaves higher (and on an odd very large instrument with 8 rows of basses also three octaves higher.
You see, there are at least 5 "charts" you need, all of which can be (and actually are) available on free base piano accordions.