If not vacuum pump, hopefully you're going to have some positive evac via the collectors? So, with evac I'm guessing assuming heads and intake are 'good'? I'd assume 960-980 with the 4500 on gas. It'd be nice if you moved the cam 2 degrees to see and report on the results. Also from what i remember the belt in those distributors would retard the advance a couple of degrees at higher speed. Either way NO judgement and GOOD LUCK!!!