Lead acid and lithium are mostly interchangeable EXCEPT FOR: lithium is fussy on end of charge voltages and low limits. In other words you get problems going over the per cell maximum voltages like out gassing and fires. My Volt pack outgasses at 4.2v per cell (199v) not good for cell life. Exceeding Low limits cause swelling and power degradation but mostly way out of balance cells which eventually kills the pack.
There's more to it than this, notice I didn't do BMS's?
The advantages to lithium: more cycles, lighter weight, higher energy density, higher circuit currents for a longer time
Your curtis can be reprogrammed to deal with the voltage limits, otherwise DC is DC until you let the smoke out. For a trial run, being very careful, you could interchange packs with no setting differences.
THIS isnt everything you need to know.