E34 - Failed MOT test (annual inspection); is it worth fixing?

Looking for advice...
I've had a 1993 E34 touring, 520i for about three years. It's in 'OK' shape; one of the front wings is starting to 'spot' and will probably
need replacing in few months, an outer sill will need patching.
It's done 178k miles and the clutch is biting right at the top of the pedal travel; I think it's the original clutch.
The dash display doesn't show the mileage (and it's not the sort that you can easily get at the capacitors to change them). The speedo has become intermittent when cold (and it is the speedo that's sticking because if I 'tap' it the needle moves but then sticks again.)
In the last six months it has started to lose a little water, say 1/2 pint over two hundred miles or so. There's no obvious cooling system leak.
So...
I think that in the next year I can expect to: - Replace wing - Patch sill - Replace clutch - Possibly replace head gasket
Right...
At the annual inspection it failed on:
1. Nearside rear brake pipe corroded 2. Front to rear brake pipe corroded 3. Offside front brake pipe corroded 4. Nearside front suspension ball joint has excessive play 5. CO emissions excessive
I don't plan to do much of the work myself- don't have the time.
So what do you think?
Are the excessive emissions connected with the use of coolant and indicate a head gasket that's on the way out?
Is it worth spending the money on the vehicle?
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Easy to change, the whole dial unit is only held in with two screws and you get get working one off Ebay for around 20, take the old one out and plug the new one it, should take no more than 10mins.
Be a shame to scrap it they are great cars, I am always sorry to see any BMW go. They deserve better than to be broken up for parts.
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snipped-for-privacy@defencecontracts.org.uk wrote in message

Not so, it seems to have an unusual design; two plugs on the back rather than four- I've looked on ebay.

Well, yes, but I'm more mercenary than that.
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snipped-for-privacy@burnt.org.uk wrote:

The brake pipes are only a tenner each or so from BMW but the rears might be a pin to fit in the original locations and I can imagine a garage charging a lot of labour to replace them. The fronts aren't so bad. Suspension arms aren't too expensive but again might set you back a hundred with labour.
The emissions might be a probelm. I can't remember now which high reading indicates which kind of problem. I recently changed the spark plugs on my car and it's like it's got a new engine.
The coolant loss might not be anything to worry about and the clutch may well last you another 20k.
For a 520i I wouldn't spend the money.
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