I have a 2005 Mazda 6 2.3 luxury sport which I broke and a brought a 05 Mazda 6 classic engine and swamped in just wanted to know what has to be transferred over
Some more details for your American readers might help. Are they both 2.3 engines? Is either turbocharged? I ask because I am not familiar with the model designations and specifications for vehicles in your country.
If, however, they are both 2.3 normally aspirated engines, it is a pretty simple swap. You will need to change over the oil pan because the AC compressor on the 3 sits in a notch cutout of the oil pan, unlike the 6. Any external sensors or different water outlets should also be swapped. In addition, check carefully the crank pulleys and see it there is a difference in which tooth is lined up with the crankshaft position sensor when the motor is at top dead center. If they are different then these will have to be swapped also. This will require you to remove the timing cover in order to replace the diamond coated friction washers necessary to keep the timing from slipping and destroying your engine. You would also in that circumstance need a new crank pulley bolt.
All in all it is a relatively straightforward project. Just make your replacement engine look identical to the one you are replacing by moving over the appropriate parts. Follow torque specs religiously and you should get a functional engine.
If you want an even better option, if there are any Ford Fusion 2.5 liter engines available in your part of the world they can be swapped in for the 2.3 with just a bit more work, and it yields a vastly better engine than the garbage 2.3