The 180 esc is the better choice, I had the leopard 3674 2200 and I have seen the aquastar 3974 2200 motor, the aquastar and a 642 or m445 would be an easy 45 to low 50's on 4s with good connectors and good solder connection, the xk 3674 should be similar to the leopard 3674 is another very good motor. But if the 3974 can fit in you boat then maybe a leopard 4092 or a tp 4060 might fit. I can tell the leopard 4092 on over power the 3674 and the aquastar 3974 on 4s. I run the 1730kv 4092 on 4s with an m545 and that get my revolt to mid to high 50's and I am talking 4s. I ran the 4092 2080kv in my revolt on 4s with the m545 and the boat was way over powered. https://www.youtube.com/watch?v=AiVMnxZ7r-Y this link has the revolt with the 2080 4092.