The last season a vintage class was run in the MRA was 2000, I believe. (Anyone can feel free to correct me). It was the last race of the day, and the grid had a field of only three bikes. Easy to see why it got the ax.

You may also want to check out the Sandia groupat www.SMRI-racing.org The last time I looked they do have vintage classes on the books, although I don't know how well they fill the grids.