Pretty much anything will work. I just stopped using a 25yo Record 7 speed mech with 9 speed Ergos, simply because it wore out. I replaced it with an 8spd version I've had for some years waiting for the inevitable. Gears work perfectly. I did also use a Nuovo Record mech with 8spd ergos in the past...
I also used the 7spd mech during my brief flirtation with 10spd. Found 10spd finicky and sensitive to perfect adj, bought a new 10 spd specific mech thinking the mech might not be up to it, only to discover the specific mech no better. eBayed the 10 spd levers etc and went back to 9.
Not so much a six pack as a barrel!
1959 Carlton Continental 1982 Carlton Professional
1987 Peugeot Perthus Pro 753 1995 Colnago Superissimo
1995? Vernon Barker MTB 1993 Colnago MTB
2005 Colnago CT2 2012 Ribble Audax