The multicarb setups on any engine are a major headache. Stay away form those. A small two barrel is about all the six needs. The two barrel unit, a Holley/Webber, for the later Mustang/Maverick 250s is a popular swap. Of course, you also need headers, exhaust, head work, a valve job, etc for the larger carbs to do you any good. Check out Clifford Performance to get some prices.
The
suspension and brakes on a inline six are completly inadequate for a hopped up six. To be safe go ahead and swap the brakes and the
suspension over to v8 equipment. The V8 hardware also gets you 5 lugs so you can actually find some wheels.