Pictures would help here,so we can tell how much welding it needs and see the general condition of the car.
Mechanically they are pretty simple to work on and parts arent that hard to find.
The engine in my own was also shot, but a replacement was for about £150 although my engine is the 1256cc
What size engine has yours got?
Rust is the key point here, body panels are available for the car, though some panels are rarer than others. This is were I reckon youll spend most of your money.however with out seeing the car, I cant fully say.
It's only worth taking on if you think it's worth taking. This part is personal preference, can't really help you here I'm afraid. As It's your time and effort going into the car.
The only reasons I can think of why 6 months down the line you cant complete is it because;
A-terminal rust, I'm mean most of the structure in the car has gone. However this could be found on inspection before buying the car.
B- lacking of enthusiasm/loss of mojo. If you don't like the car it can quickly turn from a bit of a fun project , to that f-ing thing thats taking up space on the drive which i regret ever buying.
C-lack of funds or working space.Sadly this is out of our control and can't really be planned for in advance.
How long and hard to get back on the road? All depends on your skill and free time you have to work on it. If you have all the skill, funds and could work every weekend on the car. I reckon almost any car could be done in 6months. Again. This is an individual things that comes down to you personally. However setting achievable goals is a good thing, for example, I want the engine running within the next two months.
Short summary of the above.
If you like the car and are willing put in the effort. Get it.
Just give the car a really good inspection before buying. Magnets are your friend.
I hope this helps and doesn't put you off getting a project car
Ps,let us know what you decide to do