You want one that places the throttle bores over the primary 4bbl throttle bores. The 4bbl intakes were designed to replace 2bbl intakes that way, so the A/F distribution would be thrown off by moving it back. The throttle linkage and fuel line would have to be changed too. The Edelbrock 8057 adapter does it correctly. They are made for EGR Performer intakes so the EGR holes need to be blocked with an EGR delete plate, but they are the best I know of.