82 Chevy SWB 355 timing issues!!!

[Squarebod]

I'm having timing issues I'm thinking it's to do with vacuum advance but it could be the distributor too was kinda cheap and thinking it was a mistake but it does have an adjustable vacuum advance so I'll tell you what I'm working with and let you guys decide.
I'm trying to tune a 355 SBC simple right well I'm struggling I know my way around a stock build this is my first performance build 26 years young so I got alot to learn and I'm learning the hard way performance doesn't tune like a stocker.
I ripped a 350 out of an 1982 RV it was a 4 bolt main, had a blown head gasket and a pitted cylinder so I took it straight to machine shop said he could sleeve it and said he could square it with a .030 bore job so I did the machine work and had the bore match my 12cc dish valve relief piston and had it decked to the .025 in the hole it was close already to that (keeping pump gas in mind) I'm running the stock crank he polished it up for me said it was a desired crankshaft to have (if someone could tell me why I'd like the info don't have any numbers off of it but maybe I should) running the stock rods as well had the surfaces reconditioned. Plasti-guaged as i installed to stock clearances. I'm running a comp roller cam setup @ .050 lift intake duration 235 exaust duration 249. intake lift is .522 exaust lift .509 on a 107 love see running the "kit" so everything is comp. I topped the valve train with a set of Dart Aluminum heads 64cc chambers and 180cc intake runners and a 75cc exaust 2.02 intake valves 1.60 exaust valves. On top of that is a Holley strip Dominator single plane intake and stacked on that is a 4160 vac sec Holley 750 CFM carb. 73pri/75sec jets 2.5 power valve (produces about 5.5-6hg vacuum) the distributor I'm running is an assualt racing 65k coil HEI w/adjustable vacuum advance I got a cheap Mr gasket mechanical curve kit with on soft and one med spring = about 18° seems to like it there but maybe that's where I'm wrong I've bench set my carb so that the plates are correct in the idle circuit is working properly but when I hook up my vacuum advance to "ported" (no vac at idle I checked) and soon as I start to accelerate timing jumps to some where in the 40s and my cherry bombs start sounding like the are launching artillery shells I know tuning over the web is almost impossible but hoping someone can tell me where I went wrong. Do I need an MSD box or can I make my setup work as is or do I need to change somethings up?