Oh I'm pretty happy with how mine turned out, did it in VGMM 1.1 (VGM Music Maker, a MD specific chip tune tracker) by ear which took a while. I used instruments from Castlevania Bloodlines and some other games. I'll probably try something more modern using a vst next time.
Still I'm curious how those Zero Slug remixes sounded since I love those old FM chips (they used one of them for Castlevania Rebirth's OST).