For the closest in appearance I would go with a '68, '69 or '70 Pontiac carb. If you are needing a 7027263 then You must have a 4spd car. Look for a 7028263, 7028265, 7029263, 7040263 or 7040267. Those should be the easiest to find. Check ebay from time to time. I usually see a few every week.
A bad day fishing beats any day working...and if you can drive your GTO to get there....all the better!
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A bad day fishing beats any day working!