Briggs & Stratton carb

I recently bought a craftsman tiller
Model # 917299853
With a 5 hp Briggs & Stratton engine.
Model # 135202 0145 01
It was hard to start & spit & spattered.
I took the carb off and I think it’s it’s not the original carb on it. It did not have a needle screw. Instead had a screw with a small hole at the end. And right above it. Was a pin hole on each side. (And the screw was turned in all the way. Like on the bottom of a bowl )It had a bad diaphragm and the spring and cap below it. Was stuck in the down position . I don’t know anything about this type of carburetor. Will it run normal with an aftermarket carburetor, like I think this is?
Need help with this one