If you remove a metering needle you should see a code stamped into the stem. On 122S models of that vintage I've always found ZH needles - rather lean, especially when compared to the later '67 & '68 B18 with a higher compression ratio and split exhaust manifold. Years ago I came across a soft cover reference booklet with all the SU needles listed, measured every 1/8 inch - about a zillion needles (maybe a little bit of exaggeration). -- Dave