vacuum questions

My question is about manifold vacuum on my triple 750. What is the factory vacuum settings when the bike was new. I only have 8200 miles on the bike but the carbs are from another 750.When I bought the bike I found that the needles had been screwed in so deep that the tips were broke off in the bottom of carbs.So I bought a parts bike with good carbs, and they have been reset to balance the vacuum. They are way off in balance,so I set the vacuum balance to 8inches of vacuum with a sync.tool. I'm thinking that it is to lean at this setting. It's a little slugish right at take off,but gets after it with a little more throttle. I don't know whether to go up or down with the vacuum. The bike is a 1978 Yamaha750 Special XS model. If anyone has the answer please pass it on ,thanks,Jim