If I were in the market for a 4-1/2 inch newt I would look for a Edmund 4-1/4 inch.
Manly because of the primary, and as much as I love the white tube Edmund scopes
from the earlier years I'd go for a late model red tube.
The end of the white tubes in the late 1970's saw the mirrors go from "better than 1/4 wave"
to 1/8 wave and even 1/10 wave as the telescopes transitioned to the red tubes.
Edmund started making their own optics in house about this time, and Robert Edmund
took over the business from his dad Norm Edmund. I'm not sure if these two events
factored in on the greater accuracy but it probably had something to do with it, and we
all know today Edmund Optics is a giant in the field of optics.
I would start with a stock Edmund red tube 4-1/4" and make improvements as needed if
you feel there is room for improvement.
Or a late white tube, you can tell a late white tube because it will not have saddle bolt holes
in the tube, by this time they came from the factory with tube straps which I don't care
Back to the optics.
I have a late primary and it is fabulous. Any of these Edmund mirrors are great but the late
one I have is really great I think.
Click on these to enlarge, a late white tube and a red tube.