QSRA all that well known, so nice work making that link, but to your question, the YC-14 is for all intents and purposes the QSRA’s older brother, the DNA matches are numerous, and they have at least one parent in common.

Quote via QSRA Familiarization Doc R1 via NASA

QSRA was designed and built by the Boeing Commercial Airplane Co — is a modified de Havilland C-8A Buffalo, with new wing and nacelles and four AVCO-Lycoming YF-102 engines.

NASA makes specific note of the QSRA’s high performance in the low speed regime, very low noise levels, and versatile flight control system — first one has obvious lineage via AMST aka the YC-14, also Boeing did a bunch of research into acoustics related to the USB engine configuration, much of that was interior noise measurements (see here) however also included exterior measurements and more to the point, analysis of USB acoustics in general, furthermore they did quite a bit of work on advanced flight control systems, computers, architecture, and so on (see here)

Boeing had followed along with NASA’s work on External Blown Flaps and Upper Surface Blowing for over a decade at this point, taking part in a number of wing tunnel test campaigns, and gobbling up any NASA treats à la USB if and when they appeared. From the handful of papers I have read discussing the QSRA design process, the YC-14 makes guest appearances throughout.