Unless you have lots of time on your hands, and really enjoy a challange, I would advise against it for the following reasons:
(1) The torque/HP characteristics are totally different for the engine (major re-calibration).
(2) The 1969 would have smog emission carburetors (very lean, recalibration).
(3) These carburetors do NOT have a good reputation; most MB people doing performance work replace them with Webers (real Webers, not H/W). These actually warp worse than a Rochester B!!!
(4) Parts, other than gaskets and fuel valves, would be available only from an M/B dealer, if at all. Fabrication would be the order of the day. If the parts are available, expect to be surprised when you hear the price (and NOT pleasantly).
Not saying it cannot be done, but I wouldn't personally consider it.
Jon.
