Using 44/16 on a 20" as a starting point the nearest gearing for a 24" is 39/17 (a little bit harder) or 41/18 (a little bit easier).
Using 43/16 on a 20" as a starting point the nearest gearing for a 24" is 38/17 (a little bit harder) or 40/18 (a little bit easier).
Running 43/16 on a cruiser is equivalent to running about 51/16 on a 20" - thats extremly hard gearing.
If you want to run 16T on the back of a cruiser and get the equivalent to 44/16 on a 20", you need either a 36 (a little bit easier) or a 37 (a little bit harder).
I hope that make sense