I am in the same situation. It would have been nice to know the factor by which the signals are magnified.

Mod:link to other TS's thread.
https://forum.allaboutcircuits.com/...the-raw-ecg-millivolts-mv.186634/post-1729882

 

At those frequencies a simple resistive divider will do. It is pretty easy to check whether the capacitance across the divider’s input resistor needs to be compensated with a shunt capacitance.