How much nitrous for a stock piston?

with that little amount of compression i wouldn't retard the timing at all. exemple, my 7-1 ratio 440 i had 2 150hp stages and 1 250hp stage and didn't retard the timing any. didn't ever hurt anything. you only need to retard when you have high compression. the trick is getting max cylinder pressure several degrees after tdc. read your plugs, yor looking for small flecks of aluminum, use a magnifying glass to see them. msd makes 2 different timing retards that i have used for nitrous. 1 is a single stage the other 1 is 3 stage. like cracked said rich is BAD and is how the stock jetting is set up from the factories, especially the nos brand. youi won't hurt the motor with the stock jetting but you can if you richen it up pass the stock stuff. lean it out by adding nos jet not by taking fuel from it.