My reference to the dyno software above. Anyone that has built a 340 back then like that knows those values were puffed and the dyno operators admitted there was a glitch. Biggest bunch of BS article back then.
An xe268H in that set up is a 1ish hp/ci deal. You aren't getting 1.2out of it.
There were plenty of happy engines that never made the MPH at the track back then! I was involved with an engine that was at the puffer dyno and it got run on a different one a few days later. It was down a bit on hp (double digits) on the second one and ran the MPH consistent with the conservative dyno.