Yes, it is possible to port Cobra 8.3 to Rebug 4.84.2, I have done it a month ago to test old Cobra 8.3,
@DeViL303 also created another 4.84.2 with Cobra 8.3
There are a few things to keep in mind before copying and pasting the files from my repository to flash:
- lv2_kernel.self with stage2 fail save by @bguerville and @aldostools is mandatory, this will avoid bricks/semibricks while loading stage2. If your current kernel doesn't have it, your NAND PS3 can be bricked and NOR can be semibricked when stage2 is loading. After compiling stage0, you need to add the necessary patches for CFW in the new lv2_kernel.self. Then you need to unpack CoreOS package from PUP, replace kernel and compile it again (any minor issue can be fatal when modifying CoreOS)
- stage2's hashes must be updated (I think the hashes are up to date in my repository), otherwise the PS3 may freeze at start
I recommend you to wait for someone to port and test the new Cobra 8.3 to 4.84.2, I will do it myself when my CFW 4.88.2 will be released