I've built several, two from scratch, and some that were almost totally
reworked heathkits.
Things are much easier if you start with a low deflection voltage CRT
like a 3WP1.

Most of the "cheepy" scopes got their high voltage from a winding on the
power transformer
and this is just so bad on so many levels.
I had some very good "dumb" luck in adapting flybacks from small TVs for
this purpose.

My first real scope was a Raytheon (Cosser) 50MHZ portable which is
still working well today.
My first good Tek, I don't put 2213/15(s) in that spot, was a 465M which
I now have too many of.
As a side to Mark Wendt, did you work with any "M"s in the AF?

Like many others on this list I'm now trying to "thin the herd".

Bert