Advice needed: e36 318is motorsport - Engine upgrade/swap?

Hello Fellonatics

I am in need of some advice from the guru's on this forum.... any and all info would be appreciated.

Ok the vehicle in question is my dads e36 318is motorsport (m44).... this vehicle is part of the family and has been since day 1.... the car is completely original and its nearing 400 000km's.... engine has never been opened .....

The car is now starting to feel VERY lazy and my Dad and I have come to a point where we will need to make a decision with regards to bringing the engine back to life....

We are deciding between an engine swap with a larger 6 cyl or rebuild the 4 cyl with forged internals and convert it to stroker with possibly turbo charging it.

I am for the rebuild route as i will then know that all the parts are new and stronger than before.

Gizmo ive been trying to make sense of your conversions from previous posts years ago on other forums but i am in need of advice.

Also trying to keep the budget within a realistic mark.... i expect we will only start this project at the end of the year...

Thanks in advance....