Replacing 90 degree crt with 70

[old_coot88]

If all else is doable except deflection angle, you could conceivably use a 'width sleeve' to reduce horiz deflection. That's a cylinder of thin brass shim stock, slid inside the yoke, between the CRT neck and yoke coils, and insulated (provided there's enough clearance). Slide it in just far enough to give desired H deflection. The vertical could probably be done with just height and lin adjustments.