Bryce - DO NOT and I repeat DO NOT USE CONCRETE BLOCKS TO SUPPORT THE CAR IN ANY WAY (EVEN JACKING IT UP). THEY CAN SHATTER AND SEND THE WORKS DOWN ON YOU.
Use stacked 2 x 10s such as 1 longitudinal then 1 across, then 1 longitudinal etc etc. Or a large chunk of wood on top of the jack with the wheels on the floor.