Ken,

Assuming you do not have a spa or water feature and you can dedicate the suction line to the vacuum line when needed, I think you could easily go with a 3/4 HP one or two speed pump.

I ran a quick head calc based on the numbers you provided and a high efficiency 3/4 HP pump will provide about 73 GPM @ 50 ft of head on high speed with a 4.5 hour turnover. Low speed would be about 36 GPM @ 13 feet of head and 9 hour turnover so even if you need 2 turnovers, low speed would suffice. GPM will depend on what pump you actually choose.