Welcome to the sight Dan.
Glad to hear you are enjoying your boat. We have similar boats as mine is a '78 w/470 and recently splashed as well and still working out a few bugs. As far as temps I have not saw more than 170 at wot. with a 4" exchanger and new water pump. Still playing with props 21p=3800-17p=4600 now have a 19p to try.
Keep us posted and good luck!!!
