If you can get 8 oz of fuel to the carbs in under a minute, you have plenty of flow. Disconnect your fuel lines and let it(them) run into an 8oz cup while timing how long it takes to fill.
Here's how I figure the rate:
8oz in 1 minute = 1gal in 16 minutes
at say 50 miles per gallon, that would be about 200 miles per hour before your fuel flow would be a limiting factor.
That doesn't account for wind resistance, so try to keep it at you back.
