What - as a second Morgan?
If you can do this at your leisure then fine.
The temptation might be to buy really cheap and do a full resto, but it takes a lot of effort and what was feasible when I was 30 (for example) is less so now because I would rather be out than rebuilding a car.
So a decent donor is more appealing but then it will cost more, and much of the cost of upgrading the engine will be lost on the residuals. I suppose the cheapest route is to start with a car which already has a Duratec, so then it's a very simple engine out/ engine in and a change of ECU.
What could possibly go wrong?
