Well now,
Do ya like pork or beef seems like the first question.
All the chains around J-ville like to cook those rounds to about 135� and slice real thin across the grain.
They have a high yield/lb.
Some of them have good beans and salad bars.
London broil could be real lean,could not require much trimmin', could be marinated overnight,cooked to medium rare on the grill, and machine sliced across the grain.
You'd get a higher yield /lb. than butt or roll.
The other approach would be foil it with a little beef stock and cook it until it gives up.
Makes a tasty pot roast sandwich.
.
Or,you could foil the round ,and cook as above.
Now around J-ville, a lot of chains slice pork butt,and you get a higher yield that way.
You'd need a power slicer to get it real thin for sandwiches.
Now ,since I like pork and I like to be lazy and socialize when folks are visiting-I'd do butts.
I'd throw me
some uncooked,bone in butts on at 225�,cook 'em overnight to 195� internal,foil and cooler them until near time for the festivities.
Each 7.5 lb. raw butt will yield you about 15 4 oz. sandwiches and you can do the math from there.
You should be able to pull them and reseason in less than 10 minutes/butt.
Now a 22-23 lb. chuck roll, trimmed up,ought to give you about 50+ 4 oz. sandwiches.
If you pull it out around 185�-195� it should still slice.
Above that and it will get pullable.
Now over the last 30 odd years of dealing with meat managers ,I have found 3 or 4 that could cook some.
One could cook a decent strip steak,another could fry good catfish, and I liked another's pork chops and milk gravy.
I can't think of the other guy.
Hope this helps a little.