There is good research to indicate that you need 15-20 degrees of tilt to maintain autorotation.
http://www.enae.umd.edu/AGRC/Aero/Le...giro_paper.pdf
for a reference.
My empirical research also indicates that you need a disk loading of
(number of blades * 1.25 ounces)/square foot of disk area as a disk loading
for good performance and any chance of a power off landing.
(2 blades = 2.5 ounces/sq foot, 3 blades 3.75 oz/sq foot , 4 blades 5 ounces/sq foot)
Also you need thrust:weight = 1:1 or better for decent climb performance.
In electric terms you need ~ 100 (Brushless or 140 brushed )watts per pound.
For this size model I'd start out with a four bladed heli rotor head from www.centuryheli.com
to keep the flapping under control.
Because the model is smaller and thus the L/D performance of the blades is worse you will
have a higher than scale tiltback angle, thus any flapping will tend to drive the
rear blades into the fuse. A semi rigid head with swashplate will prevent this.
If you decide to do a tilting spindle head with four blades you will need substantial servos,
probably two per axis to handle the loads.
Using a 3 ounce blade, 3 inch offset in the flaping hinge,8 degrees of roll
control and 400 RPM as benchmark, the torque required is about 100 ounce/inches per blade, on four blades you'll
double that so you will need 200 ounce inches of mast tilt torque across 16 degrees of travel.
This means probably at least a 100 ounce inch servo on each axis, with metal gears.
You will also need more tail clearance/higher main mast.

a 65" rotor is 23 sq feet of disk.
If you stick to 5 ounces/sq feet, this is a 115 ounce model or 7.2 pounds.
A 9.6 volt pack at say, 40 amps is around 400 watts, not enough, especially into
a brushed setup.
To fly a 7 pound model on brushed power I would plan on about 1000 brushed watts (~ 1.3 horsepower).
So I think you are underpowered from the outset.
I'm flying 1 lb models with 100-120 brushless watts.
I'd plan on 600-800 brushless watts total for 7 pound aircraft.

mickey