I was going to mention that. I just had an ultradyne H31 ground. It’s a 280 (adv) duration cam and [email protected]. So the valve events on the intake lobe are the same as the spreadsheet if ICL are the same.
I doesn’t seem likely that a factory 268 cam has the same 050 numbers and valve events as an ultradyne 280 cam.
Also ken at Oregon cam said the ‘68 340 cam was 221@050 according to a post around page 3 or 4. I think that would be the 4spd cam.