agreed on the low end grunt. I am going to take it one step at a time. OD and 4bbl first (4bbl has the vacuum port to hook up the vacuum advance on the dizzy) and then see what that does to my gas mileage. Hopefully, improve a bit going down the freeway! I may very well end up putting a 454 in it, but I think with the fitment issues, I am not going to mess with it at the moment. (although there is one local that was supposedly rebuilt recently, the guy wants 800 for it, still in the motorhome... I can hear it run).