After installing my rebuilt Autolite 2100 on my 351W / 69 XR7, I got the engine vacuum gauge to read a strong and steady 21 in. and idle is at factory 550 rpm when parked. But when taking it to Drive and removing foot from brake before touching gas, it gradually increases from 0-28mph! Linkage looks to be the same as when I removed the carb and everything is in place…any ideas on what may be causing the acceleration???..Thx. 
What amount of vacuum did you have before? If the vacuum is much higher than before, I would look at vacuum timing advance. Of course your cabling needs to be correct. Try disconnecting and plugging the vacuum advance hose and plugging it and see if it does the same thing.
I actually didn’t test the vacuum before the carb rebuild. I went out and bought the vacuum gauge after I installed the carb , so I couldn’t say what it was before. I will try your test Gary…thanks
Are you running ported vacuum? Manifold vacuum is too high at idle. I have seen that happen when the spring in the vacuum advance is broken or missing.
additional diagnostic testing has also shown that my tach is also off by 50 rpm, so that contributed to the false reading. Idle screw brought it back down so I am at a more respectable range now. Thanks. Thinking a tach rebuild is probably due now.