As I know Isshinryu naming convention, we just used 'Tokomine No Kon'. The source of the kata seems to be from Shimabuku Sensei's training with Kyan Chotoku.
On the other hand there is a Bo Kata "Shi Sho No Kon No Dai" which came from Taira, and it would appear Taira taught a Sho version Shimabuku Tatsuo didn't study.
I would observe the use of 'Dai' with kata is interesting. At some point in the development of kata (such as Gojushohi <not in Isshinryu as currently constituted> Gojushiho evolved into 'Gojushiho Dai', and eventually a 'Gojushiho Sho' kata was developed. On the other hand the Sho version seems to be somewhat more complicated than the Dai version. In that case it would be a reversal of the numbers.
But this is just speculation on my part, as to why various naming conventions came into existence. We'd have to turn too Karate/Kobudo historians to know more.
As for Isshinryu's Kobudo, regardless of which naming convention is used, there is enough to keep one busy for quite some time.
Bushi No Te Isshirnyu