I used the same DVD to help me with my rebuild and have had great success between this board and the DVD.
Did the bearing clearances check out OK when you were rebuilding it?
Did the rotating assembly / short block (pistons installed in bore, on crankshaft, with rings) turn over easily? It should've taken around 20 ft lbs. of torque to turn it over.
Is the starter new?
How well did the battery turn over the engine before it got drained some having starting issues?
With the back firing issue, like the guys have mentioned, double check that you setup the wiring and timing correctly. Do it over if you have to. Watch that portion of the DVD again and again. I must have watched the DVD 20 times before I started my rebuild and it fired up right away.
You'll get it. Hang in there.