Had a price of £180 plus VAT to clean and stove enamel the whole lot the correct silver. SEP Engineering in Kegworth. Bit pricey but I think that's probably the route to go.
I did my 750F2 with VHT rattle cans, prepared everything as per instruction and baked it in the oven etc, now its flaking on the edges of the fins. A bit more falls off everytime I use it, been filling it in with a large black marker pen and it's quite hard to tell it's there. So am a bit reluctant to go down that route again, although being silver it probably wouldn't be noticeable.
Cheers all.