was what I was looking for.
My thought is, option one for swirl core, with either swirl or tng core is fine. Simplest is best, and with the lower humpback portion seemingly dedicated mostly to shuttle bay / cargo hold, best to let the transfer conduit run along the top of the secondary hull. Similar to how depected to the Enterprise B MSD I suppose. I still think since there is an impulse deflector crystal of sorts, it should connect up to, and align to it. Beyond that, I am open. It looks like they took care to frame the shot of Excelsior's engine room in TSFS to avoid the main warp core / conduit (since it was a redress of the Enterprise engine room). I think that frees us to depict the core however we wish. Could be anything really. Maybe it's really neon yellow with hot pink stripes