Just picked up the frame of a Hyda Bike, and I want to replace all the parts with modern parts. I've read that this was Italian. Do the bottom bracket and headset have Italian threading?

Pics as soon as I dig it out of the van, as I just picked it up a few hours ago.

Just measured the stem and seat post. It appears to take a 21.1mm stem, which should make it an interesting project to make it rideable for me, as I'm 6'2". The seat post appears to be 25.4. Maybe it'll end up being a folder without being able to drop the seat or bars with a quick release.

Why?

Because the parts are not in great shape, and I was hoping to get longer seat posts and stems.

Did you try the Foling bikes forum? There are some peopel doing such stuff over there, especially with the R20. Maybe easyer to get help to find sources for long seatposts and DIY stems, and better rims, and better gearing and..

Many like to keep the original parts here..

I have one as i collect folders. It is one of twenty different renamed frames. Another version of it is called Bianchi. Nothing on it is normal bike parts except for the tires. Nice to have as a toy or for a collection but will be a money pit if you try fixing it up. Clean it, oil it and ride it but don't put a lot of money into it. Roger