Mazda 6 engine swap help pls
 

So I just bought a 06 Mazda 6 and I was told when I bought it that the guy put a 2010 Mazda 3 motor in it. The 06 Mazda 6 stock has a 2.3L and the 2010 Mazda 3 has a 2.5. Now for one I’m not 100% sure what motor is in it and I need to know. There’s a 2.5 stamped on the block but not 100%. When I purchased the car the clutch was slipping(taking extremely long to get into each gear and severely lacking acceleration. Because the motor swap I am unsure which clutch kit to purchase. Any help would be so very greatly appreciated