I would also consider the liklihood of electrical failures on the chassis, but with the trans & evap done so recently seems worth it to keep on rebuilding.
If you remove the breather tube from the air intake and seal it off you with thumb blowby will probably build up in the valve cover (unless there is a leak at the valve cover to breather tube). The amount of blowby can tell you some things about the condition of the engine. When enough blowby builds up, it will cause the stop lever on the injection pump to move, and eventually the motor will cut off.
On my 190DT and 300DT, nothing happens in 1 minute, there is no appreciable blowby. However, on my '86 190D, the motor cuts off in 5-6 seconds. My other 190DT takes about 26 seconds.
I would be curious as to the amount of blowby.
Regards,