As stated above, friction shifting is very forgiving of set up, along with easy maintenance. Some times you just have to try an idea to see if it works. Many things in the bike world that are stated to be non-compatible can be, and are, set up in a way that works. I have a few in-home, customized cassettes that do not shift well with indexed shifting, but they are fine with friction mode. I think the same would be true at the front dr.

To the OP, or anyone, I have a 4400 Tiagra triple with rings, available for cost of shipping, set fee box $16. The crank is 130 bcd and 170mm arms. IIRC, it is 52, 39, 30, well used but still fully operational. I can post a couple pictures if any interest.