This alone for me looks ambitious and hard to make, but i'm wish-thinking for more oldschool ideas. For now i'd like to know how much i'd have to pay for this.
I know that
https://forums.alliedmods.net/showthread.php?t=327281 and
https://forums.alliedmods.net/showthread.php?p=2631488 exists, but both are incomplete, Reverts makes weapons unable to drop and Golden Ages is not only abandoned but also crashes the server for one reason or another.
What i'm looking for is one that enables owners to set any version of every TF2 weapon via SM commands.
So if one wants say the release version of Scout's "Baby Face's Blaster", they would have to set "sm_tf_baby_face_blaster" to "1".
And if they want the "Two Cities" update version of it, they would have to set "sm_tf_baby_face_blaster" to "2".
Disabled to the current version would simply be "0".
Cvar values being ordered in chronological order. From 1 (being release), to 2, to whatever amount of versions a weapon has. This would also make it future proof in the hypothetical scenario that Valve tweaks any weapon.
As an extra would be great to have the old item set bonuses from sets like Scout's "Milkman" with the +25 extra hp (with a total of 150 hp). Also toggable via commands. "Golden Ages" already does this for the "Saharan Spy" set, take a look.
You can probably take "Reverts" and "Golden Ages" .sp's for reference. And use the Update History from TF2's wiki. You can also test some versions themselves by downloading old TF2 builds.