Dont get me wrong, I love the 6.9 but when reason comes into play, I dont see it as an ultimate affordable W116 performer.
The appetite for fuel, the complexity and cost of suspension components and some engineering oversights (like short lived front wheel bearings due to the 6.9 engine weight) are definites cons.
If you are into handling, then also get a lighter engine : the smaller engined cars are faster reacting to steering input. Power ?
Try a Euro 450SE with a few mods and the power will be the same as a US 6.9...with no hydraulics leaks or sags to empty your wallet. Just add Bilsteins.
What all these cars really need are manual transmissions or at least 4-5 speed automatics. I love my auto in my 350 but it does not help power-wise.
There is a clear logic behind that early 350SE rally car that we all know about: lightened, 4 speeds...
I once stripped a 280SE and weight reduction is very real due to the considerable weight of almost everything !
Unfortunately for me, France is a great country for a 6.9 : every shop understands how hydropneumatic suspensions work ! But at 1,30? per liter for premium, ...6.9s stay parked most of the time.
So come and get one here, the price will be pretty good :-)
Denis