Tens of millions of engines have been built with rubber timing belts. Its a
proven, inexpensive and pretty reliable solution, and yes, there have been
problems for some people, and dealers charge like wounded bulls for stuff
that maybe does not always need doing right then. I've had and seen belts
break and jump teeth, and its a royal PITA when it does.

Have you considered WHAT would be involved, aside from the gears and chains.

-All the existing plastic covers and backing plates on the front of the
engine have to be replaced with oil tight pieces.
-The lubrication system has to be updated to get oil to the chain and gears.
You don't expect a gear/chain system to run without oil do you?
- Existing components under the plastic covers that don't like oil
contamination have to redesigned/replaced.
- The front pulley and external belts would require repositioning ie
redesign.
- All clearances for engine bay items affected by a longer / changed engine
front would have be adjusted.

No-one (other than the engine manufacturer, for a new model) would even
bother trying to do this, when all you have to do follow the maintenance
schedule. And even if someone did design and build a kit, the price would be
so high no customer would ever buy it.

regards
Stewart DIBBS
www.pixcl.com/lancerproject