3 carbs on an inline six

[73 Mustang Boy]

It's not as easy as it sounds. If you look closely at you motor you can see that the intake log and the cylinder head are one piece (you cant remove the intake). To put multiple carbs on these motors you have to cut and weld new carb base plates on to the intake. Your best bet would probably be to order a 1 to 2 barrel adapter plate from Clifford. You could also go junk yard searching and find a 250ci inline 6 cylinder head with a 2 barrell allready on it, mill it to get the compression back where it needs to be, and bolt it on. With the newer cylinder head you would get the benifits of better flow and hardened valve seats. Hope I could help some.