The cars don't use different K members for big and small blocks except the 73 to 78 B bodies.
The trucks all have the big and small block holes in the crossmember.
The engine brackets from any big block truck will bolt right in. The 2 wheel drive mounts are taller than the 4wd mounts though so get the right ones.
Pickups use center dump manifolds, the dipstick is in the oil
pan which is a rear sump, and a plug is installed in the engine block dipstick hole.