Engine Swap Problem, vacuum line, vacuum advance

I have just completed an engine swap in my 1969 Nova from a 230L6 to a gmpp 350/290hp long block crate engine. Everything seems to be in place and the engine runs, but when I try to drive it, it has VERY little power. The timing is set at 10 degrees btdc and it revs up fine. It does have some trouble idling until it warms up. The car is basically undriveable in its anemic state. Any suggestions?

Answer
when you set the timing did you have the vacuum advance unhooked and the vacuum line plugged? if you did not your timing is actually set at about 2-4 degrees at the most. do you have the correct timing marks on the balancer for the timing tab you are using?
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