Hi Jeff,
I'm re-working a 1978 #1 rifle now also. It was origionally a 7X57 1A and I'm going to install a 458WM pipe then rechamber it to 450NE.
It was scheduled to be a 500 NE but Because several of us got scammed by the former member 'Richhere' it was put on the back burner until I found a good deal on a factory 458 barrel. Luckily I'm set to load either caliber!
Now it's underway again.