so, the answer is somewhere in between.
Firstly, no Troika wouldn't be acceptable -- it requires generating stats for the monsters and so on that are not directly created from the stats you could find in the stat block of a monster from any edition of D&D.
However, your new system does not have to use armor class, hit dice, or saving throws -- it can discard them. The constraint is not that it must use these things, but is instead that it must not use undefined things outside of them. Further, to the extent it does accept these things it must accept them in whatever form the original adventures present them.
If it helps, you can think of your new system as a set of houserules for some edition (or editions) of D&D so extensive that they constitute a new game BUT one that can still more or less use the content made for the game that you originally started houseruling.