I had a 75 hp on my 5.4 searider and it pulled two skiers/ringos with three adults on the boat at 20-25 mph.
37mph tops with two in the boat and no skiers. So I think you will be ok with a 60hp.
The chap who bought my boat put a 50hp on it and it goes ok, Nothing to write home about but if your looking to win any races you will need bigger.