hi Don
the 3.4 is a bastardized dohc based on the conventional 2.8 etc 60*V6 design. It retains the usual timing chain etc and employs a 'dummy shaft' in place of the camshaft, which in turn drives a shaft off the back end (distributor shaft) down to the oil pump. So that vertical shaft drops in like a distributor shaft would: from the top. What they REALLY missed the boat on here is that they should have made the cap so that it could come off WITHOUT taking the heads off (or cam carriers; which are prob more difficult to re&re - with the lifters all falling out etc!)
I have been looking at it thinking about how it could be turned into a much more straightforward dohc by driving
directly from the crank and eliminating that dummy shaft, the chain drive to it, etc etc; but I would need to have an external oil pump. Not totally undoable (Chrysler has/had external oil pumps I believe) and a great excuse to go to a dry sump pump etc if $$ is not an issue. (It is.....
)
But my (very busy) fave machine shop could do up gears and pulleys etc etc to do a drive system at not too bad $$, I am sure; it is a matter of figuring things out a bit of course but this is not rocket science either. Gears and pulleys don't exactly break new ground...