w115 240d help

[nachoman]

hi all and happy new year ( i posted this in the vintage section as well, so please delete if inappropiate mods )
over the past 21 months ive been slowly restoring a w115 240d auto.
Mostly fixing rust issues., so firewall and floors have been repaired ( even had to pull dash out )
replaced windscreen shields , rebuilt auto transmissions

however now comes the motor , it blows smoke and the diesel blow by is a problem
so my options are to repair/rebuild the motor
or a swap
Id like to keep the original transmission in it , as it has just been rebuilt
so im thinking a om617 ( non turbo ) in keeping with the diesel theme. and there are plenty of w123 300d in my area ( the turbo never came to my country )
or
convert to a petrol motor, and something like an m130 or m114
the w115 has those two firewall to chassis strut braces , so i dont want to remove them and compromise the integrity/strength of the body.



Thanks for any feedback