These are all valid suggestions, thank you.
As it turns out, though, I am literally looking for the Longshot's black fin can, as I am wanting to put together a proper Challenger II model. The Maniac (blue) and Eliminator (yellow) fins are the same, but I do not wish a paint-over effect. Similarly wood fins would only resort to if I could not find the right plastic fin can. And while I am able to find most old rocket plans online, not so the Challenger II or Longshot (2128). There is a parts diagram/card for a Longshot (1980), but that is a different rocket, single stage, balsa fins, etc.
I do own a couple of Eliminator kits, so that will be the source of my nosecone, and if necessary a yellow fin can to paint. I could also use this as my template to duplicate the fins in balsa.
Finding a Challenger II kit would be great, but I am thinking that coming across a Longshot, being much more recently sold, might be less pie in the sky? One sold on ebay late last year for 20-something, it seems.