Personally I would bite the PCC go with Option B and the full PbtA method. Having to shift not just a single target number but a range has more of a cognitive load (7-9 becomes 8-10 becomes 10-12, etc). I'd rather keep the target number(s) the same and just change the base skill to it's own modifier and go from there, flipping the standard BT modifiers around so that the +s are -s, and the -s are +s.
As with the gunnery, it then becomes a choice of whether a 7-9 during BT tactical play equals a success and a 10+ is a success with a bonus (which I think on the whole would run better*), or whether only 10+ is a clean success and 7-9 is success with some sort of penalty. For the former, it's easy: A standard Pilot has a skill of +2. For the latter, well, probably want the roll to fall at least mid-way through the partial success range lest it get too punishing, so a skill +3 or +4 would be better.
From the above, and following the same concepts, that would mean standard Gunnery skills would be +3 and +4 or +5.
* Alternately, it could be easy when things move to the BT tabletop could also just drop the narrative bits of the PbtA and just say a 7+ is a success; consequences and rewards are already built into the standard BT system. And it's not like Lancer hasn't set a precedent for this either, with a different vibe/resolution between the two types of action.
That said, if playing in a type of campaign where the PCs are expected to be novel-level exceptional cases, then a 10+ gaining a bonus remains a cool option. One easy option for gunnery could be that on a 10+ the player gets to shift the location rolled by 1 after it's rolled. So if the location roll came up as a 4, the player could shift it to a 3 or 5. Could get fancy too and say that on a 12+ they can shift it by up to 2. Other options could be some bonus damage, a bonus to crit rolls, less heat generated, or save them to generate a narrative effect (aka "The script writer is on our side!").