The way you suggests does not sound profession. Could u/QC calculate the nutrition value from canned white crabmeat and convert it to the serving size/serving that fits glass jar white crabmeat (without legmeat).
Once you got the adjusted nutrition value, put the nutrition value as the nutrition for g/j white crabmeat (w/o legmeat) and put on PAT letterhead.
Once QC/u re-calculate the nutrition based on glass jar white crabmeat, let's see if it is quite similar to the nutrition of the previous Fortune G/J label or not. If it is close, it should be correct.