For now, I would just replace the clutch. The oil burning may lessen with better care of the car, I assume you have flushed and replaced all the fluids if you are not sure the last time this was done. But the previous owner may not have used a diesel engine oil, if you have switched to such there may be some improvement after a few oil changes. If not, then consider the valve job at that time. But you will have driven the car much more and seen if any other hidden problems exist, or if that $2000 will restore the car to near new condition.

If you sell the car and buy another in the same price range, you will still be looking at most likely performing some repairs similar to the above anyway. With the car you own, you know the cost, buying another might result in higher cost repairs.