The flat side of the rods butt against each other on the throw, chamfer side faces the sides of the crank throw., this throws oil towards the cam shaft. The dome of the piston, if it is a high performance piston, will face towards the floor with the engine installed in the car. If there are relief cuts in the piston the large relief is for the intake valve, the smaller one is for the exhaust valve. Many pistons have a small notch at the top of the piston for orientation purposes, the notch always goes to the front of the engine. Some pistons will be stamped "'front" near where the pin goes thru the piston, others have a number or lettering at this location and those items usually face the front of the engine. Many assembled rotating assemblies will have the side of the connecting rod stamped with the cylinder number. Mopar engines have 1-3-5-7 on the driver side and 2-4-6-8 on the passenger side. If you look at your cylinder heads, the exhaust valves on #1 and #2 face the front of the engine and #7 and #8 face the rear of the block. The exhaust valves on #3, #5 and #4, #6 face each other. Install the pistons with the small relief cuts in that orientation and as long as the rod chamfers are properly located, the engine is correctly assembled.
Dave