engine swap 6 cylinder

[renski]

My engine is very smokey on start up and exceleration so its a rebuild or engine swap.
I would like to know if anybody has any idea how much rebuilds are?
Also which engines are a straight swap including if a diesel will fit :.
Would like a bit more power if at all poss.
The car was in practical classics back in september 2010 readers cars.

[e21-Mark]

M52 2.8 or M20 2.5 or 2.7 if you want to remain original?