would cutting the cone part of the bbk header flange out work ok, to open it up to the 3 inches that it actually is.
then making a custom 3 inch pipe to fit for running true duals. i can't afford to have ground clearance issues, and i have the headers already

 

if anybody has tried this or knows how it would effect performance , would you please let me know before i do it

 

ttt

 

either nobody has done this or nobody knows.... i'll let you know , well maybe not

 

I dont think anybody would go threw the trouble of doing that...just sell the shorties...LT1 headers any make/size seem to go quick here and get yourself a set of slp shorties or mid lenghts if you dont want the clearance issues...You should be fine running LTs though..Just doesnt make any sence running a big 306 cam and some headwork then choking it up w/ some crappy bbk shorty headers...W/ a LT1 headers is the last thing you wanna go cheap on. Obviously your not worried about emmisions w/ the 306 so just run the Lts

 

i know i don't know all the flow properties of headers, but with 1 5/8 tubes on both long tubes and shorties what is the main drawback.... is it simply the extra length to allow better scavenging or.... what i see most is the bottleneck cone instead of the straighthrough collector seen on lontubes