If I understand what you are trying to do, you are converting an irrigation circuit (likely using 3/4" to 1" pipe) to drip irrigation, and you're doing this in what you call "not a really bid yard".
Well if the pipe in the ground is only 3/4" and the total output of the circuit stays below 300pgh, then a 200' run of pipe would have at most about 4psi pressure difference.
So if I'm understanding right, I don't see what's the point of more pipe in the ground. The bigger issue is to ensure you don't have too much pressure comming out of the irrigation system. While I think most drip systems indicate they will handle upto 50psi, I think you really want the system to be closer to 25psi.
I've never used them, but I read that Rainbird (perhaps others) have conversion kits. These kits replace a spray head and include a pressure regulator, filter, and something to tie your drip tubing into. If you used these kits at each spot you want to tie into the circuit, the pressure inside the pipe would stay high all around the yard AND you'd get that 25psi lower pressure desired by the drip irrigation.