New here, just starting a 1985 E150 custom camper van build. My question is on improving the performance of my inline six 300. I had originally planned EFI headers and using an Offenhauser intake with a Holley 390, but on the webpage it states this set up won't fit in vans. So I'm back to square one. I have access to a 351w but I'd like to just improve the 300 and save the 351 for a different project. Thought? Ideas?