The GSG hardly constitutes a sentence.
The writer perhaps never left a single scrap of other writing. What do you do - line up all the bits of writing from East Enders we have to see what we think? Or just extant extracts from the work of potential suspects.
Please produce anything we have written by Kosminski?
An approach such as you suggest is neither forensically sound nor legally viable.
Any result would be utterly subjective.
Honestly, you'd get more mature judgement from a kindergarten class!