What balancer and what timing tab do you have? Are they original to that 327? Sounds like they may not be in agreement givng you a bad reading.
my 1st thought....
pull #1 plug, kick the engine over with your finger over the hole....when u feel pressure u are on compression stroke.
Now turn engine up manually ..as the piston gets near the top use a bit of mig wire or screw driver to feel the piston move.
As it comes up it stops moving at the top before goingf back down
mark the postion where it stops moving and where it starts going back down on the timing tag....1/2 way between those 2 marks is TDC...well maybe not exactly put so close it doesnt mater for what u are doing.
While there check that the dizzy is in correct position/tooth..#1 HT lead and rotor faces damn near staight forward and the VA canister pionts to just behind the passenger head light....this enables a wide scope of movement without fouling valley covers and stuff.
says it should run at the factory timing spec even with the bigger cam
yeah or damn close to it..bit more idle (intial+VA) advance thu
u do not mention changing the mixture to suit as u change timing and rpms...these go hand in hand, not just for the idle but when setting the power curve in the time to....and the cruise.
Also the dizzy u have is most proberly set up for later model ported vac engines with approiate emmission crap on,,,these curves are not interchangable
Also I doubt very much the msd is even close to the "factory timing spec " your guy is talking about.