I don't know about the Omega, but a few years ago I was driving a Ford Escort 1.8 Diesel which was a company car. The vehicles were poorly maintained, and sure enough one night while driving I heard a bang and even before I left the driver's seat I know it was the cam belt. The car was towed to a local garage (after it was first towed away to the car pound by the traffic wardens, they don't take notice of 'broken down' signs on the windscreen... but that's another story and anyway I got the fine money back! eventually...) and the engine was declared dead beyond economic repair. Problem was that second-hand 1.8 Ford Diesel engines were in great demand and short supply at the time, while 1.6 Petrol were cheap and plenty... so on the garage's (ill-)advice the company decided to replace the Diesel engine with a used Petrol one.
And this is where things started to go wrong... the 1.6 Petrol engine sourced was second-hand and what is known as 'short engine' so all the ancillaries needed to be sourced separately, then the fuel pump, fuel tank, and fuel lines needed changing, and for some reason the new engine fouled the suspension so some modification was needed there as well (and following that, the car was, as Ralf Nader would put it, 'unsafe at any speed'...). The result was that the piecemeal process ended up costing much more than the car was worth.
The lesson is that there is always more than meets the eye with these type of projects....