Check out the Portsmouth numbers found on the US sailing website !
http://www.ussailing.org/portsmouth/tab ... es06kb.asp
Portsmouth numbers are based on reported actual races and results : not numbers assigned by a commitee based on local Lack of knowledge (PHRF).
you will find PHRF numbers in a wide range for the Macgreggor x and m with most being way off reality.
your AMF appollo 15.9"" is found under centerboard class (compare your number to Macgreggors, etc ).
The Macgreggors and hunters are found under offshore keelboat classes.
You can modify and spend more money modifying a boat , but consider buying a faster design to start with if that is what is important to you. The Hunter 260 is a faster sailboat than the M and X 's , just did not have the big motor. The Mac D and C are good sailers , just don't have the best headroom. The Hunter Edge got a good review on the madmariner website, but no hard data was revealed.
I now sail an S2 7.9 (26 foot) ; it has good headroom, 4 berths, portsmouth 81 (very fast) and is easily trailerable. Small motor. A limited reproduction run is now planned. see website
http://www.sailingsource.com/s279/
Good luck deciding on deciding what boat fits you the best, but remember "When any 2 sailboats meet, there is a race !"