as for the finish...I run your basic hastings single moly top rings.
I was thinking too tight a wall moper, cause theres no sufficient oil there, thats a lot more swept and side thrust. jmo
Looking (just eyeballing the wall finish in your pic) there is too much hone mark left. It's too rough for a moly faced top ring (normal Hastings "moly" ring). The pic I posted is with Hastings moly coated ring too. Note how little cross hatch is visible. What that means is the moly gets scrubbed off immediately... Like thin paint on steel being rubbed on sandpaper. At that point, the ring is plain iron face and will need the long break in period with light and moderate load, high vacuum perods, etc. However... The pistons on the 4" engines are short as compared to the stock ones, and the rings are narrower. Which means you have less ring surface area sealing on the wall, and less stability as the piston rocks around. The loser the piston on the wall, and the rougher the wall finish, the easier it is for oil to be cleared away and material to transfer between the piston and wall. Especially with the side loading of the long stroke. You've got low pressures, leakdown issues, and oil on top of the piston, plus possible material transfer on the bores. That all says to me the wall finish isnt right and the piston is wobbling around in the bore. Hypers dont expand. I would suggest if you are concerned with that, try measuring one at room temperature and then boiling one for an hour or so and re-measuring it. If it changes more than .0005 I'd be surprised. Keep after it. You have issues that will definately "find" more power when fixed.