Just has my manifold done, at 175,000 kms.

Mine was too warped to skim. And therefore too far gone to build up with metal spraying.

What the shop did was heat it up, bend it, and clamp it.

And it cooled off straight first time. Apparently only needed very light linishing (? Is that the right term?) and they were happy. All at half the cost of a new manifold.

And try your edge on the head face, you might find it's less than straight..

Regards
Max P