We were in a similar position when we thought the belt had gone on our 156 V6. The conclusion was that the engine was fundamentally good - prior to the failure it was fine, it had been serviced rigorously, so we planned to get it fixed. Thankfully the belt had only slipped with no damage.
Is the car with a sensible specialist? If it is, they will be able to advise. If they have a "known good" engine on the shelf, they can wallop this in for less than the cost of rebuilding - and and change the clutch for pretty much the cost of the parts: it is very easy with the engine out. Then you'd have a good engine + transmission ready for the next 60K miles. I would avoid taking bets on an unknown engine, you may be inheriting a bag of bolts.
If you elect to repair - make sure that the outfit doing it are thorough - you need to change the big end bearing shells after valve contact. If it wasn't a high speed smash, then fixing the head is perfectly possible - basically get new valves and get them reseated at an engineering shop. In a high speed smash, the guides tend to go, and the head is economically scrap. Sh head is better than sh engine - less to go wrong.
In either case, it is worth doing. The current value of the car is zero (well, £150 scrap). What would a replacement cost, given that the car has been looked after and is reliable? 2K? Probably more. Either way, a specialist will be able to fix yours for between £500 and £700 at a guess. That's less than £2K.