post the rom image here. I'll check it with my own app. the royl roms can be tested well because the rom mods can be revers traced and checked due to known signature&check-sums
otherwise you should write your routines for checking blocks, checksums..mods etc and at the end..there's still the compatibility issue. if you are 100% positive that the rom works with your drive..then, before resetting the drive after flashing rom ...just download again the rom and compare it with what you have flashed. but this should be done by the tool you use...automatically. a sort of "write verify"...before reset, and brick ur pcb

here's a sort of log from my app wile testing a royl rom before flashing.
Code:
Rom image successfully tested
CRC OK.
Performing CRC on Flash Module: 0x4F
CRC OK.
Performing CRC on Flash Module: 0x0D
CRC OK.
Performing CRC on Flash Module: 0x47
CRC OK.
Performing CRC on Flash Module: 0x30
CRC OK.
Performing CRC on Flash Module: 0x0B
CRC OK.
Performing CRC on Flash Module: 0x0A
ROYL mod traced, mode ID: 0x0A
ROM dir module traced...
ROYL mod traced, mode ID: 0x0B
ROYL mod traced, mode ID: 0x30
ROYL mod traced, mode ID: 0x4F
ROYL mod traced, mode ID: 0x47
ROYL mod traced, mode ID: 0x0D
Reached the table end.
Block CRC OK
Header CRC OK
Checking block ID : 08
Block CRC OK
Header CRC OK
Checking block ID : 07
Block CRC OK
Header CRC OK
Checking block ID : 06
Block CRC OK
Header CRC OK
Checking block ID : 05
Block CRC OK
Header CRC OK
Checking block ID : 04
Block CRC OK
Header CRC OK
Checking block ID : 03
Block CRC OK
Header CRC OK
Checking block ID : 02
Block CRC OK
Header CRC OK
Checking block ID : 01
Block CRC OK
Header CRC OK
Checking block ID : 5A
Checking the ROM image file :WDC WD6400AAKS-22A7B0_01.03B0_WD-WCASY114816_DONOR\Rom Firmware\ROM_rev05.6PC.bin
it's a basic test, to ensure that the image it's theoretically "in good shape"

for the so called "marvel" roms..still standardized,..(in fact this was the first time when wd started to introduce a standard for their roms)...firmware..can't be tested..because the missing signature for the rom mods. what was before year 2004....the roms before "Marvel" doesn't have a similar format for the headers found at the beginning of the rom image..and doesn't seems to have crc for the code blocks. these roms...doesn't have modules inside..in fact the 2-3 mods are included in the starting headers...a primitive mod A (head-map)...and a adaptive mode..I think.