Shep,I have fitted a set of taper roller bearings to a spare frame I have but it's untested so I cannot say if they would be a,"Significant" improvement as both my CX with correctly serviced ball bearing systems handle superbly and attain the required standard for my Road Worthiness Certificate and my mechanic is very strict.
Tapered roller bearing may well be a better design but until my ball races become worn or damaged I can renew the bearings very very cheaply and easily,
http://simplybearings.co.uk/shop/index.php?cPath=23
1/4" ball bearings.
The stock parts are still available,
http://www.davidsilverspares.co.uk/CX500-1978/part_112697/
My 2 cents.
HelloH if you would give me some feed back on these photos. There is some discoloration in the races but I think its probably