When you refer to primary tubes, are you saying where the pipes go to the collector? Also do want them to come out from the heads as far as possible? Have noticed on some v-8s that they stick out some what and also some are swept back towards the rear of the boat. This is my first build and was wondering if I need an electric fuel pump to get the fuel to the mechanical pump or did I just need one or the other. Will have a 650 Holley on the 350 bored to 383. Thanks for any info.