Hi Rob,
I looked long and hard for a manual 530i Touring - rare as hens teeth! But I found one, and relatively unmolested. It's absolutely gorgeous! The previous owner added an original M5 body kit and throwing star wheels but other than that it is as BMW intended. So if you can afford the extra mpg I'd go for the V8 anytime, but it is widely recognised the 525 is the best all rounder (in the UK at least).
If you do go for the V8 make sure you see it started from cold, and with the drivers door open just rest your hand along the top of the door frame. Any more than a slight tremor then just walk away. Nikasil! To be honest though if you're looking at a 530 and it's done more than 70k miles chances are it'll be OK anyway.
Do get an FSH, make sure the air con freezes your fingers (if it doesn't you're looking at £600) and any wobble from the front wheels probably means new suspension bushes not just wheel balancing.
Good luck with your search and I hope you find a good one.