Several!
You’ll still have the rear vertical seams to contend with, and the rear-bottom seam… these tanks do like to peel from the top-down, if they don’t fail from the bottom center!
The overflow box should be 1/4” (technically 6mm) black smoked glass, you would be best-off also cutting this out and rebuilding it with quality silicone,,considering that a failed overflow seam means the tank can theoretically drain down to the point of failure into the sump, then onto the floor during a power outage!
The tank’s bottom silicone seam inside the overflow box poses another challenge, given that the bulkhead holes are WAY too close to the edge of the bottom pane for both comfort, and for ATSM C1048 standard… you can’t really get glass in there to brace the seam with the bulkheads in the way! (I worked around this on my project tank by doubling up the overflow box’s bottom with a second glass layer, though this comes with many of its own complications)
Regarding bulkheads, Red Sea uses a proprietary plastic “pass through” collar siliconed down to the tank's bottom pane for each bulkhead hole, with the plumbing threading through that… the last G2 reefer I disassembled had four of these plastic pass throughs peel off the glass by-hand… I recommend deleting them and using proper bulkheads in the factory holes!
All this is to say that there’s not a single drop of factory silicone on this tank that you should really trust, and your plan only fixes the damage you can currently see (eurobracing aside)!
Here’s some further “light” reading on the subject from my current Reefer 450 project tank:
https://www.reef2reef.com/threads/the-frankenreefer-450.1147222/
