I wouldn't consider it blasphemy, but purists would and if Tony, up at TSE, starts making .333" barrels, the point will be moot.
You would run the .338-333 round just as if it was the original thing, load data would be the same, as would be pressures.
As I wrote before, until I get the reamer, I won't be able to say whether the neck area would have to be opened up or not.
Any M98 action, in good condition, would do for the project.