Replacement Engine 121s02-0130-f1

I am replacing a B&S 121s02-0130-f1. Most everyone I talked with today indicated that it was on backorder. One company indicated that they had the f2 model of the same motor and that it was the replacement for the f1. Can anyone confirm that this would be correct, or should I be concerned that there is a physical difference between the engines?



this engine is off of a Toro TimeMaster 30



thanks