If you are going to do a Ruger #1 to 577, you will need to consider a very heavy contour barrel and mercury reducers in the tail--Weight should be as Marrakai suggests!!

Personally I would prefer Marrakai's 577 lite in a modern Double rifle, Made right and shooting the right fullbore ammo for the 2.75 inch cartridge it would be a dandy and ready for nearly anything on Terra firma short of a record tusker or a tyrannosaurus and it would probably handle those critters!!!!