port matching the intake manifold?

Sorry if this is a lame question. I searched the site before posting.
I have a set of fully ported 340 J heads. There is a 3mm difference between the cylinder head ports (25mm wide) and the intake manifold ports (22mm). The heads look like they are gasket matched. I'm wondering if I should gasket match the intake manifold to the same width as the cylinder heads? Just wondering if this is typically done with heads that have been fully ported. I would think that there would less turbulent flow of air into the heads. Therefore, better flow and performance?
If so, what's the best tool for the aluminum manifold? Dremel, air tool? I have never done this before

thanks