If you're having a smoking issue, then it's you're rings.
Particularly, the oil control rings. And it is not really the ring's themselves, but the gunk in the piston ring grooves that keep the rings stuck to the pistons, and therefore not allowing them to "scrape" the oil from the cylinder walls as they are designed to do......once the engine heats up to operating temperature, the rings will expand and overcome the gunk in the ring grooves and start to do their job. When the engine cools down, the oil control rings are stuck once again.
Now, this is just my observations, but I have rebuilt more than a dozen of these Mazda engines.....and to some people, not the "correct" way! Very seldom do I have the cylinders bored out and order oversized pistons, I have only gone the "typical rebuild way" with 2 of the Mazda engines that I have rebuilt.......over the last 20 years or so.
If you pull a 100,000 mile or more Mazda FE, F2, or G6 engine apart, there is a good chance that when you clean the block up, you will still see the original cross hatch pattern from the factory honing process in the cylinders! What does that tell you? It tells you that the engine block cylinders are NOT worn very much!
Mazda used narrow, low tension rings when compared to domestic engines of the past.......and most manufactures do the same now.......but the engine metal in the Mazda engine blocks (in my opinion) seems to be much better (more nickel maybe?) and harder than the domestic engines of the past. I have rebuild SBC engines, Pontiac engines, and several V6 chevy engines......and I believe that the Mazda blocks are definitely "harder" to score and/or wear down. Again, my opinions.
But, after rebuilding more than a handful of these Mazda engines, and NOT using new pistons but rather cleaning them to look new again, and installing new standard size quality rings (Sealed Power, Mahle, NPR, etc.) I have never had an engine smoke (when it did beforehand) after I rebuilt it. I currently own a 1989 Mazda B2200 that I rebuilt the engine in, sold it twice, bought it back twice, and drive it currently almost daily, and it still doesn't smoke, and it is actually quite fast.......for a Mazda! I don't know the exact miles on the engine since it's rebuild, but it is definitely over 50,000 miles now......might be over 60,000.
The things you want to look for when tearing one of these Mazda engines down is,
Heavy or deep vertical scoring on the piston skirts, or the cylinder bores......if they are present (some light vertical scoring WILL be present) then you may want to have the engine cylinders bored, or replace the pistons, or both.....however, it's been my experience that light vertical scoring is all you may see.
Of course, rod & main bearing damage, crankshaft journal rotational scoring, thrust bearing surface conditions on the crankshaft, crankshaft keyway condition (usually only the B2000 & B2200 engines), etc.
And you want to measure everything and log it when pulling the engine apart.......so you'll need a decent Dial Caliper, 1", 2" & 3" Micrometers, Magnetic base Dial Indicator, and some telescoping or snap gauges, or a Dial Bore Gauge, and a good set of feeler gauges. Then also measure the new bearing oil clearances, ring end gaps, and crankshaft end play.......and record them also. This way you KNOW the exact condition of the engine at teardown AND at rebuild.
You can use Plasti-gage also, but I prefer to measure it all with tools.
Anyway, for parts and gaskets I usually buy quality name brand products from RockAuto.com......as well as Amazon sometimes, because I get free shipping most of the time with them. Find out the manufacturers part numbers, then search them on Amazon.
I will dig up some rebuild pictures of the past, and post them here in a day or two.......I gotta go work on a project or two now!