mid '80s heads.... 2 questions

So Jake took the rebuilt 28 years ago and never fired up 318 apart today just to make sure nothing took built a nest in any of the cylinders while it sat forever under the workbench....

We have 2 choices for heads on a stock bottom end 1984 318.... The 318 heads that belong on it.... and a set of barely used mid 80's 360 heads... Both sets of heads have the smog holes under the exhaust ports...

What size tap and pipe plug do I need to run in those little holes?

If I use the 360 heads, will I be taking power away?

Neither sets of heads have been milled beyond a very minimum just to true up the surfaces..... We are installing a repro stock spec mopar 340 cam and an old Edelbrock streetmaster intake I've had lying around for 3 decades (i'm getting old...lol)