Hey, this was from a while ago....still have the carbs?
"I have a 1977 351m, 4 speed, 2150, and a 1979 400 auto 2150. I THINK, if you swapped the 351 jets into the 400 carb, you would be good to go. Heck, they might even have the same size jets.
Tomorrow, I am heading back to the jobsite, 800 miles away. I will be back home the week before Christmas. If you still are stuck, pm me and I will send you the 2 carbs. Just pay me back for the ride."