First thing first, power. My edited RocSim file said this rocket would fall back to the ground on an A motor, about 150 ft on a B6-4, and 250 on a C6-3. Parachute deployment was way lower than I liked. So modifying the fincan for 24mm motors seemed like a good idea.
The first thing that needed to be done was to modify the existing engine retainer. I decided I like the stock look, so simply removing its internals was the chosen course of action.

Next I needed to modify an Estes 24 millimeter motor retainer. I took it from picture 3 too picture number 4.

Eventually, after I glue the two pieces together with epoxy, it will look like this next picture.

And here is that glued together assembly. I masked up the non glued areas to prevent excess epoxy.

Here we have the new 24 millimeter motor mount tube. I had to make a new pair of centering rings to fit it into the fincan.

Mock up of my motor mount assembly prior to gluing it in. The hollow Q tip shaft is the pass through for the Kevlar shock cord.

And here is the completed fin can assembly. For alignment purposes, the lower body tube needed to be added to this assembly stage. This was because the lower centering ring was outside diameter sized to fit inside of the first can. The upper centering ring was sized to fit inside the body tube, which happens to be about 1/8 of an inch bigger then the inside of the fin can.