Are you sure they're not ISO images ?
I wouldn't put anything like that on anyway unless I have a HUGE SMC (256mb!)
Most of the PC Engine stuff I've got on are older roms like Ordyne, Shadow Of The Beast, Turrican etc
They all work just fine
i have sidearms working - this was only the usual small file size and i thought this was a cd only game - unless im wrong? can anyone confirm if it was a hucard game also?