Hey i see your putting the 770 truck avenger on. Great carb but sucks balls off the line unless you have a pretty serious built big block. I have the 770 also on a Buick 455 built pretty decent in a blazer and i have a horrible stumble off the line. I called Holley and talked to there "truck and street avenger specialist" and he told me that they have some check valve in the metering block that wont lift off until you get up in revs or have a pretty serious big block to pull enough air through the carb to lift the check valves off idle. Makes no sence to me since a 770 is not that huge of a carb. and he said there's nothing you can do about it all he did was offer me a reman 670 in place of my 770. but fukc that deal. Just thought id let ya know before you spend the 300 sum odd dollars on a 770. Might wanna call and talk to Holley first.
Sounds like the blazer is goin good man!