145.012.68 Dial Mystery

Grandfather of my colleague bought an Omega Speedmaster in 1968 with a reference 145.012.68 SP on the caseback. It has a 321 movement and the movement number is 26.551.XXX. It also has the DO90 Bezel. Omega document shows the production date November 1968. The watch has all ticks for a 145.012.68 we know, but it has a unique dial. Dial has a step, Long hour markers (not re-lumed), all Right hands, but the Omega logo is printed (not metal applied). I showed this watch to many collectors. Few think it may be a service dial. Other says that they got their similar model serviced in 1970s but the service dial have had shorter hour markers (similar to 871 of that time). Grandfather says that he has never got his dial replaced and it is the genuine dial from 1968. Is there anyone who have had his 145.012.68 serviced in 1970s and got the similar stepped dial replaced but with long hour markers? I request you gurus to help me out. Thanks in advance.

I think if you search here you will find several other examples of 321 service dials with long markers and a painted logo instead of the AML.