I have just found an exercise my friend did when he sent in a pig for sausage.
It was a saddleback gilt and it's dead weight was 46.13 kilo (Yours averaged 55 kilo)
Meat left for sausage once boned out and trimmed was 21.85 kilo
Total weight of sausage was 31.62 kilo
Three pigs of an average of 46.13 would have netted over 90 kilos of meat.
So based on the above the your three would have netted over 100 kilo's.