We've all done it. A couple of Y block builds ago I put a fresh 292 in a 55 Fairlane, put the ignition timing at TDC ready to fire, checked all my connections, fuel, compression, etc. Turned the key, and thankfully the hood was off the car and there was no air cleaner. Mt Vesuvius' inferno erupted out of the carb 10 feet in the air.
"Well now, that ain't right" I said.

I turned the key again for a second or two....same result.
Puzzled I looked at everything - and then found out what I had done after someone on this forum gave a simple reminder.
The distributor spins the rotor COUNTER clockwise!

Doh! Changed the spark plug wires around as I blushed and away she went, lol.
Did you check to see you had good oil pressure and oil to the top end? Since you already have all of the spark plugs out making the starter spin the motor pretty easily, it would be pretty easy to verify.
Post a photo or two when you get a chance. The new forum makes posting photos pretty easy.
Daniel JessupLancaster, California
aka "The Hot Rod Reverend" 
check out the 1955 Ford Fairlane build at www.hotrodreverend.com