Hi Carl,
LCModel is not being actively developed anymore and the source code of the helper programs (lcmgui, bin2raw, makebasis etc) was never published, so changes to headers in the proprietary formats will not be supported any longer. Your best bet is to switch your workflow to one of the newer open-source processing tools (Osprey, FSL-MRS, spant, etc.) that can read GE files of any generation and write LCModel raw files. Osprey allows you to call LCModel directly from within (optionally), I believe that the other tools might have that functionality too.
Related threads:
GE P-file header revision 28.002 and “GELoad” function - Data Processing - MRSHub Forum
LCModel error reading GE P files - MRS Software / LCModel - MRSHub Forum
Cheers,
Georg