My suspicion is that the Blood Kite was derived from the Stalker.
Doesn't share any components but mass with the Stalker. Usually derived 'Mechs seem to share at least something, looks if nothing else. The Blood Kite most certainly doesn't look like the Stalker ;D
"York XT" chassis might be connected to "Star League XT" which was used in the Highlander and Highlander IIC, later in Tai Sho, and Gunslinger by Spheroids. Original Stalker used "Titan H1". The Blood Kite's engine is without brand though the Clans have used Vlars and other such common engines, so the engine being a Strand 255 is not impossible.
EDIT Turns out, "York XT" is also used in Crimson Langur, and Crimson Hawk uses "York II XT".
Wait a sec, the old Banshee used "Star League XT" as well...
The Blood Kite is based on Khan Bogues' requirements: Low cost, durable, firepower, efficiency.
Since the Stalker was developed as the Reunification War was ending, it might have had similar requirements, so it would be just convergent design process. Those have happened several times in BT.