Goodness, I really love this thread and all its bike obscura!!

The only trouble I have with 5V cranks is how expensive they are. Thus, playing to my strengths, I have been toying with an idea lately, to take a cheap five-arm in my favorite 165 length and try machining a 50.4 spider out of the existing arms and web. This would be child's play on a CNC mill. Just a few lines of code for the arc-shaped "step" that the chainring sits on, and a few more for the bolt circle. I'd have to file a bit behind the crank arm, where the mill cannot reach. Think I should try? There's a grungy orphaned drive-side Silstar on Ebay I could pick up for $32ish, but it seems a little much to be throwing at an idea that may or may not work depending on the crank's geometry, which I cannot just go and measure.