greetings and welcome fotopom, i was in a similar situation last year, too many cameras, which to take?
like you i was comfortable with a zorki but really wanted to use 120 even though i knew a 3.5 lens would not cut it. In the end i opted for the fastest lens, 1.4 50mm on an old minolta sr7 that i had not used for ages.Used xp2 at EI 250, this worked for me as like you i wanted to participate and not have the distraction of a complicated setup. Got some weird looks from the pro but i also got some great casuals which he did not.So i would sugest fastest lens. Zorki or canon? good luck