how do i know where to set base timing on my 418 fresh build, and how fast to bring in total timing.distributor is an older mp unit that was bought with electronic conversion kit.current ignition is msd6al with blaster 2 coil, motor is 340 stroker 418 cid, 9.7 comp,ported/polished cast iron x-head open chamber.cam is herbert solid roller .246/.253@.050,lift is .585 in/.600 ex. 108*centerline installed at 103.5*,weiand x-celarator intake,750 db pumper jets are 72f/82r with 6.5 pv in carb.vacuum is currently at 11" at idle at 1200rpm,when i put it in gear, it idles little rough and vacuum drops to about 6.5-7.5 it fluctuates with the cam lope . i have a older dial -back sears timing light that i believe is reading higher than it actually is,it says base timing is 30*but it starts without any problems,im borrowing a friends non dial back timing light to verify if my timing light is indeed reading wrong.any tips, ideas.thanks mike