Assuming experienced and comparable PvP pilots on both sides...?
I think if the Chieftain goes SCB, it should be quite a tasty match-up.
Unfortunately, because most players don't appreciate that SCB = meta, most SCB FdL's will only have to face sub-standard Chieftains, optimistically built with an over-estimation of the effectiveness of a bi-weave hull-tank hybrid.
Ofc where there is a significant skill advantage the hybrid or hull-tank often wins anyway. But where both pilots really know what they're doing? SCB = king.
What I'm saying is, as the vids start to come out, don't pay too much heed to the inevitable ton of hybrid Chieftain v SCB FdL vids. They just pose the question whether the Chieftain guy has enough skill to overcome his build handicap.
The truly interesting question, ship v ship, will be SCB Chieftain v SCB FdL. I predict that the FdL will still edge it though, as even taking into account that the Chieftain has the happy options of either c6 bi-weave for better active regen, or c6 SCB for overall health pool, the FdL retains significant base shield advantage.
It could be close, though...