One problem is normal CRT's have low retention, scope tubes are high. Picture a dot starting slowly on one side & fading out as it goes. In the olden days there were projects to turn a B&W into a scope.
The other problem is messing with a SS set, you will probably toast many
hoz outputs ! It would be an interesting project but I wouldnt spend
any $$ on it. Alt is keep the normal scan rates & feed it much
like a monitor at the video outs. You will uses low level voltages at that
point & not burn things up.
73 Zeno
LFOD !