Hey there Richard - I'm usually on the Chrysler Inboard page....I've got a '70 Buehler.
I'm glad to see you on this forum becuase I saw the youtube videos a couple of weeks ago. Nice boat. I'd love to see some more pictures.
I'm not positive but, I have a feeling your boat may actually be pre-'68. In addition to the left-drive (the last of which were made around '64-65) the Interceptor could be a giveaway. By 1966, most, if not all, of the engine options were Chryslers. That same year, the lineup also underwent a drastic facelift when Buehler hired Virgil Exner (famous car designer) to redesign the boats.
Get in touch. If I can't tell you whatever there is to know about your boat, I can introduce you to people who can.