Pretty good job! Nice touch of yellow tape on the rims with roller brakes.
The lack of replacement rims for the Mini must rank as a fatal shortcoming, since rear rims tend to wear quickly. (I have stopped using rear brakes for that reason.)
Velocity have a 28H 305mm rim in their catalog. I vaguely recall you had no joy from them...?
Looks like quite a long wheelbase - what is it?