Those shifter/levers won't work. They are designed for V-brakes and pull a different amount of cable to the cantis you have fitted and they'll either no exert enough pressure or be like and on/off switch. You either need to convert to V's or get a different set of levers and to be honest those Acera ones are awful. Have a look for some used Deore LX ones for Cantis which come up fairly often for less than £20, they are much nicer and will more importantly work with your brakes.
If it was me I'd be looking to move the whole bike towards a Deore LX setup as it's period correct, nicely made, functions well and doesn't cost the earth.
Carl.
If it was me I'd be looking to move the whole bike towards a Deore LX setup as it's period correct, nicely made, functions well and doesn't cost the earth.
Carl.