Did I Miss the Autogyro Thread? Looking for some technical information

If I missed it if some kind soul cold point me in the right direction. But if not...

My next build is going to be an ugly foam electric autogyro (I expect to crash it, the second one will be prettier.)

Conventional front engine airplane fuselage maybe 24-30" length and 22 ounces ready to fly.

How do I figure out the correct size and number of rotor blades? There's a lot of inexpensive helicopter blades on ebay in the 300-400 mm range.

Do I need to tilt the rotor head forward a bit?