The first serial number R7911 was made in 1954. That serial number range is R3100 to R20800. If it is a Sweet sixteen it will have a gold plated trigger. I do not think this is a Swt16.
The second serial number X07754 was made in 1947. That serial number range is X1001 to X13666, again if it is a Sweet Sixteen it will have a gold plated trigger.