There was a time when you'd look for a dead Metro to harvest a complete 1275 lump. If you're looking to swap just the engine there are a few extra differences to be aware of:
You'll need a primary gear to match the engine, possibly with the other 2 transfer gears to make a matching set.
You'll want a crank damper that not all 998's have (yours should if it's a later model, but the original for the engine is better).
The water pump pulley and top hose and radiator bracket are also different. As is the layout of the engine breathers, which may cause you clearance issues with the radiator fan and brake servo (if you have one).
