Just so I could understand a bit better I did a diff of your binary vs the original. The change is highlighted in bold.
$ xxd MarvelVsCapcom2.bin > a ; xxd MarvelVsCapcom2_unlocked.bin > b
$ diff a b
132941,132944c132941,132944
< 002074c0: 0000 0000 3047 4242 0101 0001 0001 0101 ....0GBB........
< 002074d0: 0000 0000 0000 0000 3047 4242 0201 0001 ........0GBB....
< 002074e0: 0001 0101 0000 0000 0000 0000 3047 4242 ............0GBB
< 002074f0: 0301 0001 0003 0101 0000 0000 0000 0000 ................
---
> 002074c0: 0004 0000 3047 4242 0101 0001 0001 0101 ....0GBB........
> 002074d0: 0000 0000 0004 0000 3047 4242 0201 0001 ........0GBB....
> 002074e0: 0001 0101 0000 0000 0004 0000 3047 4242 ............0GBB
In an attempt to try to learn how to live patch MVC2, I used the following Netboot memory reads, to see your changes to the unlocked rom vs the original.
You can use any triforcetools.py, or Naomi_boot.py, etc. and just borrow the functions and force it to print out hex.
import binascii
print binascii.hexlify(DIMM_Read(0xA0200000+int(sys.argv[1]), int(sys.argv[2])))
$ ./netboot_upload_tool_OSX_HighSierra.bin 192.168.1.2 MarvelVsCapcom2_unlocked.bin
...
$ python naomi_boot.py 29908 68
0004000030474242020100010001010100000000000400003047424203010001000301010000000000040000304742420401000100010101000000000004000030474242
$ ./netboot_upload_tool_OSX_HighSierra.bin 192.168.1.2 MarvelVsCapcom2.bin
...
$ python naomi_boot.py 29908 68
0000000030474242020100010001010100000000000000003047424203010001000301010000000000000000304742420401000100010101000000000000000030474242
I had noticed the "0GBB" strings from my previous memory diff during a quick glance around 0xA0200000 as you guys mentioned.
nLOADING GAME NOW...
LOADING GAME TEST NOW...
LOADING TEST MODE NOW...
0GBB
0GBB
0GBB
0GBB
0GBB
0GBB
0GBB
0GBB
MARVEL^E VS.CAPCOM ^D 2
New Age of Heroes
0 0 0 2 2 4
J A P A N
MARVEL^E VS.CAPCOM ^D 2
New Age of Heroes
0 0 0 2 2 4
U S A
MARVEL^E VS.CAPCOM ^D 2
New Age of Heroes
0 0 0 2 2 4
A S I A
MARVEL^E VS.CAPCOM ^D 2
New Age of Heroes
0 0 0 2 2 4
E U R O
I attempted using the following as writes with no success:
HOST_Poke4(addr + 0, 0x00040000)
HOST_Poke4(addr + 32, 0x00040000)
HOST_Poke4(addr + 74, 0x00040000)
Am I remotely on the right path?