Ray, I think the Americans were a lot less experimental than the Aussies were/are. The original integral head sixes for Ford Falcons, Mustangs and Econoline vans progressed from 144, then 170, then 200. Mavericks, in the early '70s, could still be had with a 170, 200, then 250 sixes. I've seen one '79 Mustang with a 250 six. I believe by the '70s, only the 250 six was available in vans. These engines were avoided by many, because of their integral intake, but others found suprising performance from them with minor work. I had a '65 Mustang 200 with dual headers, an Offenhauser tripple carb intake* and a Iskenderian cam. With no other modifications I could give 260 V-8 Mustangs a fit!
* Holes were drilled in each end of the intake and an aluminum adapter was bolted onto the factory intake, provind a mounting surface for the two extra carbs (with progressive linkage)....worked like a champ!
