After ploughing through the various bits of info I have I can say the system DMW initially used in the early 50’s seems to put model number first, then a letter showing whether a standard (rigid) or de luxe (Sprung) frame with finally a frame number having the year of manufacture as the first two numbers with the build number following.
I couldn’t stand up in court and swear to this but it fits this particular frame quite well.
Model 44, S for Sprung, 54, made 1954 and 359, the 359th made that year.
A low frame number isn’t surprising for a firm like DMW. They weren’t a major player plus they were going gangbusters making their MP Tele forks at the time as well.
So there you go, I think your frame is straight DMW as is the number. I don’t know how easy it is to find an early set of MP forks for it, but a later set would be far more comfortable. The early ones were shockers.