I have a 91 R3500 with a 454 in it. I replaced the motor with a rebuilt one out of a 77 motor home. I used the original peanut port intake on the oval port heads. I also put in a Summitt # 1301 cam with a new double roller timing set. The cam was recomended by the Summit rep for fuel injection. The cam specs are .500 lift with .218-.228 duration at .050, with a 114 centerline. The salesman said this would work ok with TBI. The problem I have is low vacum signal to the map sensor. Is the peanut port intake compatible with the oval port heads.