I'm not 100% sure, but AFAIK the syscon hash checks were implemented in 3.55.
Anyway what I suggest you do is, after duccessfully downgrading to 3.55-nocheck (after the full downgrade process, aka going to service mode and installing pup etc), make another dump of your NAND/NOR, then downgrade to 3.41 using the service mode downgrade. If it bricks, just reflash your NAND/NOR with the working 3.55 dump you made after downgrading.
EDIT : Wait, just thought that the PS3 needs to be powered up for you to flash the NOR, so this might be a bad idea, since if 3.41 does actually have those checks, it will try to turn off your PS3 when you try to boot it, leaving you unable to flash. Wait for some answers from people with more knowledge than this.
PS3 Slim CECH-3004A 160GB
PS2 Slim SCPH-70004 - FMCB 1.8b