try dropping the timing to around 10 - 12*. and make sure you hook the vacuum advance back up. then test drive it and see if that helps.
were the spark plugs in the heads? if they were then you may have blowby issues. i'd do a compression test and leakdown test and see what you come up with. you will hear a certain amount of air rushing past. but it shouldnt be so easy to turn by hand.
hope this helped!