Kinda depends on the year/version of the A999.
The early versions (starting in approx. 1978) did not have the lower 1st gearset, those started about 1980ish.
As far as stall speeds go, (and it may vary a bit year-to-year) the '68 FSM lists the A904 stall speed behind a stock 318 as being 2125-2425 RPM (stall if used behind a 340/360 would be a bit higher, maybe in the 3k range- the amount of available torque will increase the stall speed on the same convertor).
The '91 FSM lists the A999 stall speeds as being 1800-2100 RPM for units used behind the 3.9 V6, and 1700-2000 RPM for the 318/360 convertor. Using the V6 convertor behind a 318/360 would again increase your stall speed just like the 904 does.
I don't have the stall speeds handy for the early '78-'80 A999s, so I can't speak for those or if they use a higher stall speed to compensate for having a higher 1st gear...
Lots of variables to consider, so not the Y/N answer you were hoping for; but I've done my best to confuse the issue and muddy the waters...
:lol: