Well I managed to do the devil's job and feel I should share the experience to help others. First of all the manual does not cover all required procedures. It does highlight the necessity for the lifting, supporting and cradling activity of the engine and box. It does tell you to remove the fixing screws for the sub frame and suspension bottom joints.
What it does not tell you (And Im assuming the manual was based on a P1 car mine is a P2).
1) The exhaust heat shield and support cover are thro bolted from above the heat shield with a captive bolt assembly , 2 nuts on either side. The nuts are easy but the captive plate assembly remains in place sandwiched between the floor and the heat shield. Man handle with some force the heat shield or remove all pop rivets is only choice. The sub frame has these bolts passing thro it and cant be removed without doing this.
2) Nightmare time. Two bolts thro the sub frame are for locating and positioning of the steering power rack on top of the sub frame. These are approx 3 inches long in old money, and pass thro a tube in frame, preventing the application of release fluid or direct heat. End result with any bi metallic corrosion is they dont move and snap off despite careful efforts with a torque wrench in reverse. Replacement bolts could only be fitted after welding on nut head and an eternity of stud extraction, dremel cutting and applying heat. OMG !.
3) Re aligning the number of bolts to the steering rack , anti roll bar etc needs careful planning whilst raising the sub frame back up to fit. (I used cut off bolt heads in the rack for alignment as your working blind) removing them once frame back in place and inserting the NEW locating bolts.
4)You should also have to hand NEW ball joint bolts for refitting the suspension bottom joints. One either side. Could not purchase these local only on net, hence a delay.The original items suffered on removal and were not really serviceable.Alfa/Lancia items.
5)Even with sub frame removed the alternator only just clears the surrounding items, be patient.Bottom bolt thro alternator is very tight against inner wing but can be removed with a bit of jiggling. Top one is easy.
To summarise, I fully researched this job before carrying it out. Im a reasonably competent DIY car mender with many previous mightmare tasks over 40 years. What the dealers and specialists tell you IS TRUE !.They ( 3 companies whom I wont name) all quoted in excess of £350 - £450 for labour only, two of them with the PROVISO "Providing everything is free and can be removed". I picked up a Lucas refurbished exchange altenator for £120.
I confirm it is a nightmare, I also confirm it COULD cost you a lot more if problems such as those I came across are not easily resolved.It is a minimum total £500- £650 repair.
The good news is everything is back in place suitably copper greased for when I probably have to replace starter motor some time in future. My car has 86K miles and a T reg.
Trust this helps anyone wishing to have a go at what could be saving a GTV 3.0 V6.