Weren't all the genuine Shellsport Escorts Twin Cams or 2 litre OHC? I do remember the Kelford Cams Mk.2 Escort that was a 1600 X-flow that went as you put it.....like stink!
I don't know if that particular Halliday Escort ever raced as a ShellSport car crunch. I was only posting that bit of info because a current photo of it was shown earlier in this thread.