I have a 1980 Moby and I can get around 35. There are three models if you didn't know: A,B,C. depending on if you are after or before 1979 A is the fastest or C is the fastest. Anyway, the difference is a series of parts that limit the speed - I've slowly upgraded mine from the midgrade (25mph) up to the level I am now.
I have another Moby that goes only 25.