Downflow Furnace

Another HVAC question from yours truly, it will probably last forever. As previosly mentioned I have to change things in the light of my remodel. The question now is can I convert my gas oven to a descendant ascendant? Thank you again.

Unless it is relatively new and is a "Multipoise" oven, it probably can not be converted. The most recent can be converted to whatever area you need.
Old ovens were spent running up, down, horizontal.
You do not give model numbers and serial manufacturer to find out.

Unlikely, they are made aware ascending or descending when made at the factory.