Are you set on the 1x4? The reason I ask is that you might consider a 2x1 intake, some adapters and a pair of 1974 pinto 5200 Holley/weber carbs. Those are progressive and a pair on your motor would work pretty much out of the box. I started with a vintage weiand intake for my 261 with that set up and it ran very well with nothing more then an idle adjustment. Those pinto carbs are progressive with a primary and a secondary, running two of them is not troublesome and the look is terrific. I am not sure how to post pictures here but if you send me a message with an email I will send you a photo of the set up I was using.
That being said, and I do not know the answer to this, you might call clifford and see if they sell a 2x2 intake for the GMC. I purchased one last year for my 261 with a pair of 38mm weber DGEV carbs (non-progressive). Runs unbelievably well. Has a water chamber already cast into the bottom of the intake and you can run a few types of two bbl carbs, you just switch adapter plates. Same deal with the photo, I can show you that intake as it is on the motor now.
Last edited by mdonohue05; 04/12/17 11:15 AM.
