I shoot with a number of Bullseye competitors who converted their MKIII's to MKII's with a Volquartsen part kit. This is the only way to go with a MKIII. Reassembly of a MK1 and MKII is difficult enough without having a magazine safety. Getting that hammer strut to align with the mainspring is frustrating enough without a magazine safety preventing you from getting the hammer forward. It is like the hokey pokey
Put the magazine in
take the magazine out,
put the magazine in,
and shake it all about.
You do the hokey pokey
and toss your Ruger about.
And, the earliest chamber indicators were dangerous and caused malfunctions. A bud bought a MKIII when they first came out. His pistol would stove pipe several times before the ten round magazine was empty. The chamber indicator rested directly on the rim of the case in the chamber and knocked the case off the bolt face during extraction, resulting in stove pipe jams galore. The fix was to mill off the wing that rested on the rim. In doing so we figured out, if you dropped a loaded Ruger MKIII on the loaded indicator, the force of the drop would be transmitted directly to the case rim, probably discharging the pistol!. That really made us wonder just what whiz kid was responsible for the design of the MKIII, and whether anyone at Ruger had ever shot the things. Ruger had a recall but we had fixed the problem and after seeing Ruger's Version 1.0, bud and I had zero confidence in whatever Ruger proposed for Version 2.0.
It is obvious that the MKIII was a horrible design iteration, Ruger obviously wanted as few changes to their tooling and production line and came up with this abortion. At some point, they took a simple and successful design and modified it to the point of incompetence.