'68 sqback miss

[XTGU21A@prodigy.com (MR FRANK S LAWSON)]

We've recently picked up a '68 sqback.  The body is in great shape.  
Runs good except for this d.... miss we just can't seem to get ride 
of.  We've rebuilt the carbs, changed intake manifold gaskets and 
reset the timing.  Usually after one of the fixes the miss goes away 
but comes back.  We're trying to get it to pass Calif Smog.  Thanks 
for any suggestions.
Frank Lawson