The late Lark pedal assembly depends on the firewall, dash and steering column for support. In a 60 Lark all 3 of these are in a slightly different place/ the angle of them is different. I do not think it is a terrible situation, and can probably be done. I'd say use your angle finder and take measurements and you'll see what is involved. A 63 parts car or parts from it (including the fire wall support) would come in very handy. Original stude disc brakes need the late spindles.