Posible swap for my 273 Barracuda 1966

Some told me my gears are changed but don't know number. If I only put a 360 what I need? 318 (no poly) is a good idea or is just some better? Here a 318 used without trans cost me 1100$ aprox and the 360 that told you (I think is from a truck because owner told me it have about 160hp) + 727 torqflite is 2000$. There is a stroked 440 but is another history