Regarding your SD‑ported 6X‑8 heads (264 cfm).
Depending the a amount of port work done to them some grinding may be necessary on a "Tomahawk" intake as well.
See posts 18 & 19 here:
https://forums.maxperformanceinc.com...omahawk+intake
Other comments within that thread might be of interest as well.
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__________________
'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 )
Old information here:
http://www.hotrod.com/articles/0712p...tiac-trans-am/
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Best time 5.13 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension
https://www.youtube.com/watch?v=qDoJnIP3HgE