Lots of previous discussion about the one piece vs 3 piece oil control rings. Look it up.
A couple of points: it is unlikely that the Emgo pistons you installed have Hastings rings, unless somebody has access to NOS Hastings rings. According to Hastings, they don't make rings for Nortons anymore.
If you are looking for a one piece oil control ring, they are available through Heppolite. Not sure if they will fit an Emgo piston.
You will see from the previous discussions, the Heppolite one piece ring can be very difficult to install. And has tons of initial drag on the cylinder wall. Some folks find this unacceptable and either modify the expander ring, or won't use them at all.
Some folks have found them to be acceptable.
Pick your poison.