I've an alternator off a Volvo, (KAD44) I think it's 55A, I'd have to check. It had its capacitors blown when the power lead corroded and broke from the terminal on the back of the unit. I've never bothered to have it fixed as I had to buy a new alternator for a quick fix. If it's of interest I'll go find it - it's in the garage somewhere!
I would take your old alternator down to a decent vehicle scrap yard and compare the mounting points with what they have got available. You also need to consider that revs that your engine and the donor achieve as I would guess they need to be similar. IMHO. Paul
Thanks folks. Having researched other threads I now think I need 80 - 90 Amps and have started trying the scrapyards. Also Halfords have a super selection or rebuilds but have no data on them other than car model - I'll research which cars have alternators that would do and see if Halfords have the right model. Another benefit with Halfords is that they give you £25 if you subsequently take in your old alternator!