@rhgrafix wrote:
.... Here's a screenshot of abcde....

If all the characters are of that plain-and-simple nature, made up of only straight lines and circles/arcs, an .SHX font could presumably be defined [I made one once!], so that you wouldn't need any replacement routine but could just type the Text. In those particular characters, the exact extent of the open ends of the arcs in the 'c' and 'e' might be slightly different, because of the nature of defining octant arcs in shape definitions, so it would be important to know whether that kind of variability matters. And it would be necessary to see the shapes of the other characters, to evaluate whether they would work with AutoCAD-font-definition possibilities. [Or, if there's something about what you use them for that requires them to be Blocks and not Text, that kills the idea. Is the replacement with Blocks only because you have Blocks of the shapes you want but don't have a matching font, or is Text something your process can't work with?]
Kent Cooper, AIA