Port match intake/gaskets/heads or not

It will help, how much it helps is all in how you do it.
I try not to "gasket match", I attempt to "port match".
Why? As rmchrgr said, there's always going to be a bit of a discrepancy between laying the gasket on the surfaces, and how the parts (and ports) actually line up when assembled. Remember, we're talking thousandths here.
It's somewhat unconventional, and far from perfect, but here's how I go about it:
I pre-assemble the long block using USED gaskets- before bolting on the intake I make a thin paper "gasket" that I sandwich between the used intake gasket and the surface of whichever has the larger port- head or manifold. In your case, the head. Use the gasket as a template to cut the paper one, leaving the ports uncut. Use a bit of your favorite tack adhesive (or a couple dabs of grease) to hold the paper to the head surfaces and gasket, and bolt the manifold on. This will shift the gaskets into their installed positions. Then remove the manifold, leaving the gaskets stuck in place on the heads.
Now with the gaskets in place, pierce the paper gaskets with a sharp X-Acto knife and cut out the ports, without disturbing the gasket position. This makes the gasket match your head port size and shape. Coat the manifold flanges with blue machinist's dye. Now spray some spray adhesive on the intake manifold flanges and reinstall. Remove the intake again, this time being careful to remove the gaskets as a unit with the manifold, still attached. Set the manifold upside down on your workbench. You now have a template to scribe the manifold to the exact size and location of your head ports when installed. The actual port alignment between the two may surprise you. Scribe, remove the gaskets from the manifold and grind.
Not perfect, but darn close.
So, why go to all this trouble and not just use a gasket and grind both ports to match the gasket? Well, are you sure the gasket is orienting itself the same on both mating surfaces, and side to side? And when ported out to the full gasket port size, what happens to the gasket when you torque the manifold to the heads? It compresses the gasket. The gasket displaces and bulges into your newly "matched" ports. Same issue if your gasket doesn't perfectly re-align with where it was situated when you did your "gasket match". It may not be a lot, but we're talking thousandths here. So much for a smooth transition.
Allowing the gasket to remain larger than the ports gives it a bit of leeway for the gasket squeeze. You may have a bit of a gap at the mating surfaces, but at least the ports will be aligned.
Again, not perfect; but it's as close as I can get it.