... the ability to create 6th and 7th level spell slots.

In the Dungeon Master's Guide's "Modifying a Class" section (page 287 of the 8th printing) they give a table for variant spell casting - using spell points instead of spell slots (pg 288). The table is essentially the same as that used by sorcerers to create spell slots (i.e. it costs 2 spell points to cast a 1st level spell - the same thing as using 2 sorcery points to create a 1st level spell slot).

A 6th level spell slot would cost 9 spell points and a 7th level spell slot would cost 10 (if you wanted to go further 8th level slots would cost 11 and 9th level slots would cost 13, per the DMG).

I think it would go a long way to making Wild Magic Sorcerer's more appealing without making them outshine the other sub-classes and it fits narratively as well (learning to control your wild magic even more).