Hello

I've been given a presumably 50+ years old Mal Rees Ahead of Time. It looked quite heavily used at first and did not get any better after a few attempts to dismantle it (mostly unwanted :/ )
Here you can see the photos of what is remaining (couldn't work out how to post photos here)

https://goo.gl/photos/TYzx7A95etuVn6EYA

The frame was custom built for my granddad, but since we have very similar built it should fit me well. Its quite rusty and the BB area got a bit damaged during dismantling. Tubing is Reynolds 531, according to sticker. The fork had a broken off bolt stuck in it, I've tried to get it out, but it have broken off... even more. So I've tried to use the drill, but apparently damaged threads on one side.
For some reason only one wheel remains and the hub looks quite worn out, along with cones. Almost all bolts that I've tried to unscrew would crumble before turning. I've also thrown the stem away as it had more rust on it that anything else, might have been a mistake though.

What I'm trying to find out is, is it worth restoring? How much should be reasonably spent? Shall I try to find parts from the era or just use modern parts? What parts would be suitable for such frame? Can anything be reused from old pars?

I've heard that old bikes are nicer to ride due to different geometry used, so now I'm wondering if I should give this bike a chance, or invest in something modern and made of carbon.
I would be quite interested in restoring this bike as a project, but I would hate to find out that I've wasted my time and effort after its done.

Thank you for reading.