I’m confused. Are you basically asking for a FET driver for the BLF GT? That won’t work as you’d burn up the xhp35-HI. If you plan to swap in a xhp70.2 then the conversion kit is about the only way to get the correct mcpcb.
Are you asking about a different model thrower light? Does it happen to use the same diameter driver as the GT?
If you just want a different sized FET driver for a different light, Lexel makes those here.