One word of caution with the universal chassis. I bought a Wei-Ya replacement for my K7000 and was disappointed. There was significant blooming and the screen would brighten and then dim when the screen transitioned from one screen to another. I have seen others reporting similar complaints.
Agree. I've tried both WeiYa (Alva) and JenShin (8Liners aka Atlas) in both the 19 and 25 size, and the JenShin win
hands down for image sharpness (no blooming), none to least amount of geometric distortion with most donor tubes, and no image pulsing based on screen brightness changes.
Well worth the extra $20. Note that I used the low impedence versions not the high impedence vesrion that a 4900 would require, so don't know about compatability with your existing tube. I seem to recall seeing some posts here about some issues with either G07/4900 tubes/yokes, but don't recall which, as they vary between 40 and 55 ohms, and whether it was a WeiYa or JS problem.
In that case, plus the fact you say it already has screen burn, I'd just recommend grabbing a tube from a TV (free to nearly no cost at garage sales/thrift stores/side of street/relatives) with low impedence and ordering the 8liners chassis. You won't be disappointed in that. Another minor benefit is the 8liners have onboard isolation as well.
Just mount it all in your existing 4900 frame and you're set, then remove the yoke from your old tube and sell it with the dead 4900 board and recover a few bucks from it, someone will probably pay $10-$15 for it on the auction sites.