You might try running GSM before booting your PS1 game. Normally PS2 code can't have any effect on PS1 mode, bu GSM can force a specific HDTV mode that will influence PS1DRV to boot up in NTSC or PAL as desired. Don't know if GSM's y-axis offset will have any effect, though.
Chip-free/MC-free homebrew <3
FMCB 1.93 on MC for emergencies, NA
250GB HDD/FHDB 1.93/OPL 0.9.2 (GSM and non-GSM)/PS2 games, NO HDDOSD
80GB HDD/FHDB 1.93/POPStarter rev12/OPL644/GSM0.37/PS1 games, NO HDDOSD
SCPH-75001 (sitting idle, slims suck):
FMCB 1.92 on MC