objection! lol
the satin balls recipe is not something i came up with - and i don't even endorse it all that much, since the ingredients aren't particularly great.
i agree with the advice that has been given above, don't try to put on weight too fast, especially not on a large breed dog.
ration the food, don't let him gorge on food
or water, feed a good quality food and add a supplement like nupro or missing link. feed small meals often for the first couple weeks, then slowly transition to two meals a day.
you can give an egg or some cultured yogurt and cottage cheese and other extras, but i'd wait with that until he has adjusted a bit.
i'm sure he'll gain weight just fine from being fed a good quality food on a regular basis. don't worry about it too much.