I'm happy to report success! http://www.venturers.org/Forum/images/smiles/icon_biggrin.gif
As Pilot suggested, the solution was to loosen the handlebars in the risers (left risers in place) which allowed me to rotate the bars up and down as well as slide them from left to right - creating enough slack to let me get those throttle cables out of the throttle housing.
It was a two-minute job after that to reroute them from in front of the fork tube to behind the fork tube.
As best I can tell, the cables are coming out from the left side of the steering head and just come through now behind the fork tube.
There is still some tightness that I cannot seem to do away with on the right, but it is much reduced and I'm now not worried I may be over-stressing something.
Just took her for a short ride http://www.venturers.org/Forum/images/smiles/action-smiley-083.gif ('cause I'm only wearing shorts, t-shirt and sneakers -but I did add gloves and helmet!) and went around some normal neighborhood right turns with no handling issues nor throttle problems.
Next step for me is to get the bumpers back in place and make a minor throttle position adjustment on the handlebar and I'll be able to call it a done deal.
Thanks again, Pilot, for your help. http://www.venturers.org/Forum/images/smiles/action-smiley-030.gif
I think if anyone else adds risers, they would be well served to perform the throttle cable reroute portion of the job as soon as they loosen up their handlebars from the original postion.
And thanks to my son, Wynn (he's 11), for helping hold the throttle housing while Dad put the cables back in place - without using any bad words, either http://www.venturers.org/Forum/images/smiles/icon_biggrin.gif