I wouldn't say that the cost of the parts would be a major problem.
a set of rings for a 240D ...$138.59
main bearing set $ 63.44
valve guides $ 13.63
gasket set $ 53.21
cylinder sleeves $32.00 each.
The labor would be the most costly element., I would think.
maybe I left something out.
These are Fast Lane's prices.
I'm pretty sure that parts for a humble Nissan would cost more than this.
Semibodacious Transmogrifications a Specialty
1990 300D 2.5 Turbo sedan 171K (Rudolf)
1985 300D Turbo TD Wagon 219K (Remuda)
"Time flies like and arrow, yet fruit flies like a banana"