Unless the jets are worn, they are probably OK. You may need a mixture
adjustment. SU parts come from Island Automotion in BC (250) 479-5482
or Joe Curto in New York (718) 762-7878.
You probably ought to check float valves and float level setting.
Do you ever have trouble with hot starting? That is a symptom of
float chamber overfilling/flooding. How's your gas mileage?

You can put on valve stem seals with the head in place but it takes some
trickery to keep the valves in place. If I were you I'd get the mixture
right first and then see what is going on elsewhere. Usually valvestem
seal leakage shows up on hard deceleration and immediately following, and
the rest of the time is not too much of a problem. The oil smoke smells
oily but not "toxic" while the gasoline smoke (black) does really smell
bad.
--
George Downs Bartlesville, Heart of the USA!