Here is my opinion.
You are most likely going to find that the #16
heads have around a 75cc chamber if not milled.
Pistons are generally .015-.020" down in the bore.
Felpro head gaskets are 4.3" in diameter and come in .041" or .039" thickness when compressed.
Using these numbers in the Wallace Compression Calculator Compression Ratio Calculator - Wallace Racing
you can get an idea of what the cc's will be needed for your valve reliefs so that you can get a compression ratio around 9.0. Going 9.5 could be a little on the high side for iron heads (but doable with the right cam/timing) but most likely need 93 octane. If you shoot for 9.0, better chance of getting 91 octane at most gas stations wherever you go. So you could go 9.0 and probably up to 9.3. You can also go under 9.0 and still be good with the right cam choice.
Now compression is assuming you are not at any great altitude like Denver. If you are at higher altitude, then you want to raise compression. So assume you are at a "normal" altitude like the rest of us.
Plugging in the numbers into the Calculator, I used 400 .030" over, 4.25" stroke, 75cc heads, deck height .020", gasket dia 4.3" w/.039" crush.
With a 30CC dish
, compression is 8.94 Pretty close to what you want. Get your head chamber down to 72 cc's, and your compression is 9.14 - Perfect.
With a piston down in the hole .020" PLUS a head gasket crush of .039", you get a quench/squish clearance of .059". Not ideal, but OK as this is factory. A better number would be closer to .045" with forged piston.
So option #2
. Heads are 75cc's and you go with .027" Cometic head gaskets. Your compression becomes 9.13 BUT your quench/squish area is now .047". Now you have both numbers pretty much ideal.
With this, you DO NOT have to deck the block unless it was needed to square the block up or if the deck surface showed any signs of warping. If the deck surface is cut, this would then change all figures above and you would then have to recalculate for compression.
Some do like to "zero deck" the block which means milling the block down so the piston top is even with the block surface and not below the surface the .015-.020" it is from the factory. If this operation is done, you want to consider the quench/squish distance. Zero deck and a .039" head gasket might have the top of the piston much to close to the head, especially when things expand when hot. The .041" might also be to close for piston/head, but could work if all things were perfect. The .045" is a better clearance between the piston/head. So to use either of these Felpro gaskets, you would not want to "zero deck" the block, but rather, have the piston set below the deck .005", so the Felpro .041" gasket plus .005" deck height = .046" of quench/squish clearance.
Bottom line? You will need to know and calculate your head chamber cc's, piston bore, how far down in the hole your piston will be, head gasket thickness, and then select the closet cc dished piston to get you to the compression you are looking for.