Numbers on the chainstay nozzles:

I could swear I came across other examples of numbers stamped like that but now I can only find one, a Macario frame:







Stay ends:

The mystery Cosme:





Stay ends treatment is generally consistent with Macario frames:





Brake bridge:

Brake bridge style is more/less consistent with both Macario and Marotias.

The mystery Cosme:



Macario:



Marotias:







So, at the end of this long ramble, what we have here is a frame with clover cutouts, number stampings, stay ends and brake bridge consistent with Macario, stay caps mostly associated with Marotias, stickers from a shop that is named after Cosme Diaz who built for Macario, and finally a panto that resembles Lorenzana brand that was involved racing in the mid 80s and had frames built by Candela.

My money is on this frame being either a Macario or a Candela.