repair cam journal

[Brian]

My machinist has had a bad day!! I had him grind the journals .010" undersized to suit the cam bearings. The cylindrical grinder he uses has a fast traverse in to within a few thou of the journal to be ground, from where he uses regular infeed to achieve finished size. He was in the process of setting machine up and got distracted by a customer, returned to job, thinking he'd done the initial setup, and promptly rapid fed the grinding wheel into the centre cam journal, taking out a bit chunk, probably about 1/8" deep! Never done that before in 30 years said he!! [although, at the time I'll bet the language was a tad more colorful!!]
So, he asks if I've got another cam. Normally, that would be the quick, easy solution; to merely use another cam. Not this time though....This is a steel camshaft that I shipped from New Zealand to our collegue on here that put his rendition of the 'famous' L100 grind on it, and shipped it back. This was not a cheap exercise by any means.
So...any suggestions on the best method of repair of the damaged journal? Bear in mind, it is a steel item, not cast iron. Mig welding is a solution, but I'm worried about keeping the thing straight. Admittedly, it can be straightened prior to finish grinding, but every cam lobe needs to maintain perfect concentricity too. What do you guys think of some form of epoxy repair? There is an oil groove through the centre of the journal, and the damage is confined to one side [half the journal]. Does anyone know of a suitable 'cold process' of building up the gouge? All opinions appreciated, thank you.