in order to get a proper chassis that is not going to be a headache you will need to measure the yolk with a LCR meter. you need to find out what the inductance rating of it is. otherwise you end up with a chassis that the image is all warped and the lineairty is all screwed up..or worse case it works for 10 seconds and blows on you.
Wei ya has some pretty decent chassis meant for replacing older units, they have some meant for high induction yolks and some for low rated ones. people have had moderate sucess with simply measuring the resistance of the yoke, but to properly mach a chassis you need to test it with an LCR meter. To enable you to match a chassis to a yoke you will need to have two types of meter,a standard multimeter for the resistance and an lcr/inductance meter for the inductance.
Guessing yoke readings is not a good thing, an unmatched chassis will fry the horizontal output stage and in the extreme could kill the yoke
Lcr meters are always available on ebay at very reasonable prices
You need to read both resistance and inductance of each of the two parts of the yoke,vertical and horizontal.
Normally you find red and blue is the horizontal coil,green and yellow the vertical
Therefore you would set the multimeter to ohms and place one probe to the red and the other probe to the blue to give horizontal resistance and so on.
with all these readings you can send them to the distributor or use them to order one online.