On the '77 with its brake booster, the HS4's might be a tight squeeze...I use HIF4's on cars with the booster.
Either way, though, you'll need great motor/transmission mounts & a set of the K&N cone filters....they're the best filters for clearing the booster & providing max air flow.
& the new motor/transmission mounts ensure that rear fuel bowl on the HS4 doesn't get broken by hitting the booster.