[Arran]

 It's up to you of course but if it were my set I would probably change it back to using a 6A8G, as the 6A7 normally uses a larger and taller envelope. As both Ron and I mentioned, electrically it won't make any difference electrically but I don't really like keeping mods if putting something back to original, if feasible, which is one of the reasons I also remove aftermarket phono jacks and switches. The exception being something like Ron's recent 42-720 project that has a bad power transformer but originally had a 6X5 rectifier, it's difficult to find a tube type power transformer without a 5 volt rectifier winding so why not change it to a more rugged type that also has an octal base.
 I know the type of socket you mean, Amphenol made decent sockets, some molded Bakelite, other Micanol, others porcelain, you could get their sockets both with and without a mounting plate, both use that clip or retainer. If you look at the bottom of the socket you will notice a series of key-ways to keep the socket in place on it's plate, which has a locating key. Amphenol sockets and connectors were very popular with test equipment manufacturers, many tube testers have the sockets mounted the very same way you describe, but  it means that the socket sticks up above the chassis/panel up to 1/8'', and if the socket is in line with a row of others along the back edge it's pretty noticeable.
Regards
Arran