I haven't seen that member on here for a while unfortunately. But yes Magnum heads require less ignition advance because of the closed chambers with dual quench pads. Provides faster combustion than old-school open-chamber LA heads so the 'fire' doesn't need to be started quite as early on the compression stroke.
Regarding vacuum advance I run it on any engine that takes it which is every engine I've worked on lol. Only time I'd ever bother NOT trying to run it would be a high-compression engine on the edge of pinging or a dedicated race car that won't see any street use. I've found recently as well that manifold vacuum can and sometimes does work better than ported vacuum; both my Duster with a 450-hp 360 and '72 Dodge truck with mostly-stock 360 run better after I hooked vacuum advance to full manifold vacuum. I just set the initial timing first to where it was happiest then hooked up the VA. Idle speed didn't change a whole lot but it is more responsive off-idle and is also smoother when going from coast to part-throttle.