-Single arm work is probably a great idea. If one side feels “off” its probably not working like the other side. This is how imbalances start. and doing only bilateral work makes it worse. If its been two years, you may be a little off.
-Really get on those rhomboids/lower traps/mid-back area. The mid-back stabilizes the shoulder blades, which control where your arms go. Scarecrows, seated cleans, cuban-presses, blast strap rows, fat-man pullups, etc. The stronger your mid-back, the better you can tuck your elbows, engage your tri’s, and take stress of your pec.
-I’m not a doctor, but IMO after a tear, the muscle is going to be “tight.” In effect, one pec is “shorter” than the other. The bottom of the bench press or fly is where the stretch is greatest. If your one side is tighter that the other, the “bottom” of the lift won’t be same on both side. Max ROM on the injured side is not as long as max ROM on the good side. So, if you can, eliminate the “bottom” of chest moves for awhile till ROM improves. Maybe…
-3 board press, then 2 board press for awhile. Basically, bench press to whatever board still feels “good.” Work the bench press from this board for awhile, then as strength and stability improve, drop a board. You could also use the Sling Shot, or The shoulder Saver Pad, or even a rolled up towel or something to cut the bottom off the bench stroke.
-Chain Flies. Do flies with chains. At the bottom where the stress is greatest the chains pile up on the ground and deload off your chest. As you fly, leverage gets better and you lift more chain. Thank Josh Bryant for this awesome exercise.
-Really focus on your shoulders and tris. Unless you tore the pec in a tramatic, sudden accident, your training is what lead to the injury. You gotta be smarter now. Do you need to do those full range, wide grip bench presses? Maybe some militarty presses, partial close grip benches and cable flies are a better idea.