Not sure where you are in the world but I'm guessing the UK with 1000 quid, but it may be worth checking with the Police.
In England the law would find you guilty of disposing of the equipment, whether you intend to keep it or sell it to another. It's known as appropriation - ie treating someone elses property as your own.
This could easily be classed as theft / handling stolen goods.
So with an apparent crime being committed there is chance of some form of investigation - CCTV can be checked etc. The streets won't be pulled up but worth a try.
Also may be worth keeping an eye on Ebay, local second hand stores that specialise in instruments. I would also call every music retailer in that area. Musicians would surely look after one another (barring the odd unscrupulous individual) so the more eyes looking the better. Also, another musician is more likely to spot a vintage instrument than your general Joe Bloggs.
Further more use the most powerful system in the world - the press. Play on it, tell them it belonged to whoever you like - a dead relative for example. Anything to get people looking and spreading the world. Another valuable tool is the word ' reward ' it doesn't have to be millions, just use the word. The reward could be a scabby sweet wrapper, but it's still a reward.
I'm no musician but I can appreciate how much this would mean to you.
Wishing you all the luck in the world
