DON'T run a single 4bbl. on a tunnel ram (except for pro-street etc.) of you want to increase performance. Also DON'T run too small of carbs on it. Forum gurus will tell you to run 2 x 450s and other nonsense. 2 x 750s is about the minimum for a healthy 440. We ran 2 x 660s on a radical 383 and it was perfect, if not undercarbed. A 471 B with Eddy heads just swallows up 2 x 850s. A friend put 2 x 450s on a tunnel rammed hot 340 and lost .5sec (slower) over one 750 and a single plane. Bought another identical 750 and used it with the old one on the same ram and gained back the .5 and another .3 (.8 sec better with 2 x 750 vs 2 x 450s on a 340!). Listen to people who have DONE it successfully.