Easy 1 mate,find an old fiat tempra,lancia delta 1600tc turbo,lancia dedra1600,1800 or 2.0,fiat tipo 2.0,fiat croma 1600.
They all have the same injection system fitted(Weber/iaw) and the valves are all the same.
I fitted a spare valve that i got off a lancia dedra 1600tc and fitted it on my Vw corrado T.16v that i retro fitted with Pectal super 8 injection from a sierra cos. built by GGR and mine works perfectly,although it's a bit noisy.
The difficult bit might be finding the Italian motors in England,over here in Rome they are 2 a penny in scrappys.
1 other thing which amazes me is the Cosworth rs500 fuel regulaters that are sooo rare now,on eBay they go for 100+squids when all you have to do is get 1 off 1 of the above mentioned motors and drill a hole opposite the fuel return,add a spare fuel barb and bobs your uncle, you have a regulater that supports 8 injectors for which you payed peanuts.
Same goes for the idle valves,40,maybe 50 quid used 'cos people THINK that their Cosworth specific items...,demanding big money.