Big block or small block

I am ready to give my duster some more power, any thoughts on powerplants. Trying to decide on big versus small block. Car in question is a duster with a 4-speed. Looking for opinions based on personal experience in regards to cost for horsepower and handling.Also are you happy with your engine or would you do it differently if you could do it again? Car will mostly be street driven. Thanks in advance for your input.