I have driven the old Elan and you are spot on that its a fantastic handling car, but have heard stories from many friends about restoration projects. Generally they take much longer and much more money than you expect. You only need a couple of bits missing, decide to upgrade something, or break something and costs/time escalate.
If you really want to take it on, budget the subs cost to Club Lotus, magazine and club advice would help.

I'm on the look out for a Caterham, but having driven a couple on the road, and hired a couple of times for track days, not conviced how much road use I would give one.

Its very hard for other road users to spot you ( being so small/low down ), and there is very little crash protection, especially from a side on impact. They are a handfull in the wet, and generally for 5 minutes of fun there is 25 minutes of pain.

Although you do have roads ( if not the weather ) more suited I guess.