Bob runs a 3.9 on his carb. I have a 3.5 and I put the Edlebrock carb on my truck. I used the EDELBROCK PERFORMER SERIES 500 CFM Part# 1403
I would recommend the 390 from Holley because my carb is just too much for the little 215 V8. I have had to jet and needle it down a lot. I bet it would settle in nicely if I have the 3.9 instead of the 3.5.
Still, even running too rich, the truck has a lot more oomph that it did with the side drafts.
I am running at sea level. I never gave much thought to how I would tune if I lived in Denver.
Firemanshort
1980 Stage One
(Past owner of 1973 Series III - Highlander)