I suggested the FD-1056 because the inner plate has a shifting aid to help with non-ramped/pinned chainrings. I believe this was Shimano’s attempt to bridge the downtube/STI eras. I have done a setup one on a bike with the original ST-2300 and a 1056 it shifts quite well with flat rings.
But if your chainrings are set up with shifting aids, I would think most likely if the bike came with Tourney ST-A70 STIs, you can go with a later FD, like a 5500. 105’s are Shimano’s lunch pail level. Good quality and performance in a pretty tough package.
John