I've had two 1970's with Shaker Hoods and stripes. One I still own (repainted, never restored) is a 1970 Mach 1 with 351 M-Code and the build date was 10/14/69. It has the solid black stripe and built in New Jersey. The other was a 1970 428 R-Code with a build date of 11/05/69 and built in Dearborn with the solid hood stripe. Neither car had the "351" or "428" call-out numbers in the stripe.
I also had a cousin who returned from Vietnam in the fall of 1969 and purchsed a new 1970 M-Code Shaker Mach 1 off the dealers lot with the solid stripe, no numbers.
I was going to college back then and had a new 1970 Grabber Mustang (F-Code, no hood stripe). I was a big 1970 fan and looked at all of them I saw back then. I really don't remember seeing the call-out numbers in the hood stripes back then. In the years since it seems like most Mach 1's I see at cruises and shows have the numbers in the stripes. I like the look, just don't remember seeing them like that in the fall of 1969 when the 70's came out.