The trick to reassembling the H&Rs which have the sear/sear spring captured in the trigger guard, is to whittle a wood toothpick to size, then putting that in the rear trigger guard hole to secure the sear and sear spring. That "slave pin" then holds them captive while you reassemble, and then use the real rear pin to push out the slave pin once the trigger guard is placed in the frame correctly. (You'd need 3 hands otherwise and still won't get it, so use a slave pin from the start and save an hour of frustration. Ask me how I know this...)
Have fun with it, and good luck.