I agree with some of your choices although i disagree on afew
such as ....
Roth/ Gronevelt
no way Roth was more devious and thought he would live for ever to quote Micheal Corleone where as Gronevelt knew that death was nearly upon him and was ready for it gronevelt left his shares in the Xandu to cross where as Roth would never do anything like that.

*Carlo/Jimmy
Jimmy was not involved in the hit on Silvio it was just Jimmys brothers
where as Carlo was in on the hit on sonny
Jimmy seemed more honourable even at the end he went outside rather than be killed infront of his new wife Rosemarie.

*Sonny/Silvio????????????????????????????????????
is my biggest concern Silvio was a soft boy never intrested in the family buisness he wasn't part of it where as Sonny was tough and was a hothead and wanted to be part of the business

Althoug hi must admit
bits of Mcluskey are very obvious in Jim Losey