The pad on the end of the rod is to counter balance the gudgeon pins mass. Do not remove it. It is also used to balance the rod. Unless you have shaved the rods to polish them do not bother rebalancing as they are very close as it is.
I have had a look at a few old pistons here and yes it's OK to shave the crowns . They will be better anyway,with less moving mass at high feet per second rates. Imagine the piston coming up at several hundred feet per second,then being yanked or pushed back down again ,..the strain is enourmous .
I am building few engines here at moment and an old friend has a stack of rings made by Teves and thompson. The Quality is absolutely beautiful!. Some of his stiock is close to 50 years old so I doubt if Teves still make rings ( may have been bought out by TRW in the 70's I think) .
Do not remove metal from the flywheel etc. The old thinking of less mass equals more horsepower has been debunked now with many Drag racers etc fitting heavier mass flywheels to increase torque effect. on all out circuit race engines they run without flywheels ( sprint cars etc ) but that is at the outer ends of engine speeds.