I have the same prob, ended up buying loads of gloves from Sermoneta when on hols in Italy. They sell sized gloves up to 8. Their shops in Rome have HUGE choice. They have a shop in Burlington Arcade as well, but I haven't looked at the range there. You can buy online from theme shop.sermonetagloves.co.uk/
but I would recommend trying them on first to ensure a size 8 is OK for you.
The other alternative is Dents. The have an online shop:
I've got just the thing for you: TallFingers! TallFingers is an apparel company that designs gloves specifically for men and women with long fingers.
Full disclosure, I founded the company, and founded it because I ran into the exact same problem of trying the gloves that fit my long fingers. Check out TallFingers.com, I'm positive we'll have exactly what you're looking for.