If you build it with weight in mind, it's not hard, but you need to have light
everything on it, focus on it.
Luckily, I ride a 56cm, so a sub-20 Simoncini was not difficult. 20.4 with cage and pedals. I could have gone carbon on both, plus the post.
Modern-wise, a Wraith was absurdly easy to build, steel with carbon fork, at 16.34 lbs, with non-carbon post and stem.
Campy Carbon would have been lighter, or a non-ISIS bottom bracket.
