Consumer level TVs of this size never had any sort of geometry circuitry on board. Any distortion would be a function of the yoke design.
I have a feeling your original capacitor is fine as is and the pincushion error you're seeing is normal (remember that flat displays have spoiled us with their perfect geometry, perfect purity, perfect convergence, etc.).
Since the cap is old anyway, replace it with a good plastic one. Old scrapped plasma sustain boards are a good source of quality plastic caps in those value ranges.
John
EDIT: I have some caps in that size from a plasma. The brown one is 250V and the larger blue one is 315V. If you'd like one, I can stuff it in an envelope for you.
