Around 20 years ago there was a fellow in the Fraser Valley that built up a 7.62x51 Nato on the Ross platform MkII, with the single solid locking lug on each side of the bolt head.
I first met the fellow at a HACS show in Renfrew. I had a box of assorted Ross parts that weighed close to 30 kilos. I had been carrying that stuff around, from show to show for over a year. I traded him the whole box of parts for a sporter MkII.
I really wish I could remember his name. I can still see his face like it was yesterday, but I lost the associated name, along with others after a bout of chemo. He looked to be in his late fifties and lived in the Chilliwack area.
He was particularly pleased to find several bolt heads and extractors in excellent condition for both the MkII and MkIII types.
He reconfigured the bolt face by getting the face welded to add metal and then Harry Nicholson machined the face to the proper dimensions for the 308 Win. He was a tin basher and had modified a magazine to accept an feed the 308win case. He commented that his biggest problem had been getting the cartridge to feed from the box and up onto the ramp reliably. The rails and ramp were designed to accept the tapered body of the 303 Brit.
He was very motivated and excited about the project.
I saw him for a couple of years after that, only at the Renfrew location. The rifle was supposedly completed, after a two year ongoing basis.
After welding and machining, he had to get the bolt head re heat treated. I seem to remember he had to send it to the US for that. The same was done with an extended extractor.
Then, he just didn't show up any more. To bad, I've wondered, on more than one occasion what happened to him and his interesting project.
The strength of the actions is well documented. PO Ackley really liked them and tested them. I believe they were right up there with the 98 Mausers.
The Russians built up Running Bore match rifles on their surplus spares, based on their 7.62x54R.
So no fears about strength.