I've got a '95 Camaro Z28 LT1 and I'm wondering if the K -member will bolt up into a '73 Nova?

No it won't, but the LT1 and 700R4 will drop in just fine. Transplant the computer and wiring and you will have a very nice drivetrain. My El Camino has a 1989 TPI engine and 700R4 with the factory computer and sensors minus the catyltic convertor. It is a nice driver with good mpg. The rear disc brake set up should work on your Nova rear differential housing.