vacuum advance

i just put a crate 350/330hp motor w/ gm hei distributor into my 70 chevelle. i've had some problems with timing, carburation, and advance so i took it to a mechanic to take a look at it. he adjusted the timing, and carburation and told me that my vacuum advance was kicking in too early. it tends to die at stop signs or when i first put it in gear. i know they make an adjustable vacuum advance, would this be the way to fix this problem or should i go with new springs and weights? i also noticed that after he changed the timing, it had less power. i assume that he had to compensate for the early advance by retarding the timing. the spec sheet says to set the timing at 10btdc but i'm not sure if that can be trusted. the camshaft specs have been crossed out and new numbers written in. anyone know how to tell what the timing is just with the lift, duration and centerline? the mechanic also told me i could just disconnect the vacuum advance, i tried that and noticed a big decrease in power. thanks.

Rich