The esteemed gibot123 is quite right; the grass is not always greener....aren't you really saying you are....tired of your Alfa? If the noise starts when you add electrical load, I would have thought the noise is probably coming from the alternator... Or electrical connections are poor.
But if you are certain it's the bottom pulley, I'm pretty sure I have a good 2nd hand one; yours, for the cost of a drink! ( of course, you'll have to come and get it!)
Have you investigated the starter relay? If the fail to fire is accompanied by a click, it could well be that...just a thought.
I'm fed up of seeing these awesome cars going for peanuts on eBay etc; does anyone know how many 156 JTDs are left? Not trying to pressure you into keeping her! But I still can't find any other car that can do what the 156 jtd can do, ie, not too big/ heavy (159), superb performance, good mileage ( often even with a 'heavy foot'), good capacity( sportwagon), fantastic car for long distance...and that styling. It's an unbeatable combination. As long as the chassis is not eaten by corrosion, I can't see why they can't do massive mileage; I look at the suspension issues as 'consumables' with a finite life; don't see why a few squeaks is cause for scrapping...and you've already shelled out for the SMF conversion...alright I AM trying to change your mind....!
Let me know if you want the pulley
Hope that helps