Thanks, Dave. That's looking pretty good!
The reason I asked about the front of the running boards is that the actual Squad 51 had unusual running boards that curved up without a sharp corner. They were very different from the ordinary running boards you see. Yours is pretty close, but as I remember them, they appeared to be one piece and curved; they appeared to be stamped rather than assembled (of flat pieces) like customary.
You have the curve on the bottom/front outside, but as I recall them, the top curved with it rather than having a sharp angle.
Keep in mind, however, it's been a long time and memory may be faulty. I'm looking for my stuff ... (laid-back term for reference material) on 51. I know I have some pix of the running boards because they were so unusual.
Great project! Looking forward to seeing your end product.