Thunderforce AC would be an excellent addition to fba
you have a genesis core so the C2 stuff should be easy.
key points
different vblank irq (the vdp vblank irq enable is ignored, the irq level is different and it always happens)
different palette hardware - the internal VDP cram isn't used, instead external palette hardware is (with different sprite / bg palettes and banking)
the protection - does palette banking and some other checks (ribbit is probably the most annoying case)
additional sound hardware
there are a number of other games with genesis based hardware too (puckman pokimon etc.) which would also be easy ports.