When you have the cam gear installed at 6PM and the crank gear installed at Noon, the motor is timed to fire #6 spark plug. Before you button up the timing cover, turn the motor over one complete revolution, so that the cam gear is at Noon and the crank gear is at Noon. That will have both valves closed and the ignition set to fire #1 spark plug. Pull the dizzy and re-insert it with the rotor pointing at 5:30PM as viewed from above the motor. Leave room between the vacuum cannister and the intake manifold/firewall so that you can twist the dizzy body to advance or retard the ignition timing after the motor is running. Run #1 plug wire from the 5:30PM position of the dizzy cap to the #1 spark plug. In a clockwise order, insert each subsequent wire according to the firing order 1-8-4-3-6-5-7-2. Condition your brain so that you know 1-3-5-7 are on the driver's side and 2-4-6-8 are on the passenger's side. Your 2 longest plug wires will be for cylinders 1 and 2. Shortest wires will be for cylinders 7 and 8. Here are some wiki articles that I either wrote or had a hand in writing that may help you......
http://www.crankshaftcoalition.com/w..._compatibility
I know you said you're running a roller cam, but you should still know this info in the event you ever build another flat tappet motor......
http://www.crankshaftcoalition.com/w...ips_and_tricks
http://www.crankshaftcoalition.com/w...op_dead_center
http://www.crankshaftcoalition.com/w...stment_SBC/BBC
Please pay particular attention to the valve adjustment tutorial. I'm thinking you have the valves too tight.

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