Another update... I forgot to consider the bump in amperage due to Mah, so the batteries I initially ordered threw my RoF back to a whopping 24 RPS lol.
Using some logic and the equation for Watts (power), I found a suitable battery. W = I x V where I is the current in amps and V is the voltage.
The 1200 MaH 7.4v 25C/50C lipos had a total power of 444 watts (using the 50C burst rating as I won't be shooting 10s+ continually) which gave me around 18.5 RPS. In order to get 19, I needed a little more power so I ended up finding the 25C/35C 1800 MaH lipos which had a total power of 466 watts, giving me right around 19.3 RPS.
If you're in the same boat, use the above formula if you have a target RPM achieved with a known battery and you want to use a new battery to adjust the RPS.