Higginbotham Dock, Vishweswarayya Silo, Stewart Terminal and Laplace Orbital in the BD+49 1280 system for the 8A Power plant.
Laplace Orbital (BD+49 1280), Cooper City (LHS 1228), Miklouho-Maclay Silo (LP 355-65), Rutherford Hub (Hehe) amongst others have both the 8A Power plant and 7A Thruster.
Laplace Orbital and Archimedes City (BD+49 1280), Cooper City (LHS 1228), Miklouho-Maclay Silo (LP 355-65) amongst others have 7A Thruster.
the best system seams to be BD+49 1280, which has multiple places that either sell one or in the case of Laplace Orbital sell both at the Li Yong-Rui "control" system 15% discount with large landing pads.