good idle...no rpm

[Matt in Alameda]

I have a new rebuilt engine. 1948 59AB .......
....sat for 10 plus years before I got it....and 4 years more after I bought it. Starts up and idles at 670 rpm......as I push down on the throttle it goes to 1200 rpm and then it sputters and makes cackling ,for lack of a better word, sounds out the exhaust and will not go any higher in rpm. I am very much in the learning stage and I would like to know the following....what are the symptoms of a blown power valve (Holly 94)?......what are the symptoms of a massive vacuum leak?.....I have a new Crab distributor when you set the timing, you simply loosen the screw on the side of the crab and move the little metal plate up to retard or down to advance correct? I have some e-mails out to individuals, but I need this shotgun approach as I am going crazy after working and waiting on this car for 8 1/2 years. Thank you all, who respond....Matt in Alameda