We had a '77 Dodge van with a custom 440V8 that we did in fact start by getting it up to 40 MPH, then shifting from neutral to drive. On other occasions, it was under its own power at 60 MPH, placed in neutral, the key changed, turned to run, and the transmission moved back to drive. The engine refired, and we continued driving. This sort of thing was common.
We had a '78 GMC pickup that had a bad starter. It was common to park the truck at the top of a hill, and start the truck by letting the truck roll down the hill, then shifting to drive. That happened for 2 weeks, until we got the replacement starter. That truck was odd, though. It had L1 & L2 marked on the gear indicator.