Get your money back for that engine. You'd have better luck fitting it into the space shuttle. You can not turn a four cylinder into a six cylinder any easier than you can turn a car engine into a jet airplane engine.
Fitting the wrong engine into your car is going to cost a lot more in parts and labor than buying a newer and safer car. Engine mounts, cross member, (part of the frame), radiator, fuel pump, coil springs, Engine Computer, engine wiring harness, transmission, exhaust system, power steering hoses, and many other parts will be different and need to be replaced.
If you need a different engine, this is the opportune time to buy a car in which you are less likely to be killed in a crash. You'll spend less money than going through the expense of replacing the engine with the proper one.