Heartbreaking as it may be, I think you should be on the look out for a new frame. A couple years ago I bought a really nice, smallish 80s Bianchi road bike that I thought I could "make work". Added a long mountain bike seatpost, long Nitto technomic stem, and a set of moustache bars to replace the drops, and it still never felt right. So I sold it and moved onto other things, after wasting a buch of time trying to make it work. Luckily the guy who bought it was as tall as me (yes, I told him it was too small) so he ended up taking the stem off my hands too.