Tango, with this kind of build spec, here are some things to consider.
You don't need a 2 stage trigger for a 4" group at 100. A good GI single stage trigger will get you there and you can stone the surfaces to easy it up a bit with no extra cost.
A JP spring kit is a great, durable upgrade that doesn't cost a lot, but is worth it in my mind.
You don't need to free float the fore end for this type of weapon, but it will greatly increase your accuracy if you do.
Buying a full LPK is a great way to save money and they are for sale all over the net at silly low prices if you look around.
A standard A2 stock is fixed at 13.5", but will be cheaper than any of the adjustables out there.
Hit me up, I might be able to find you a few parts in the back of the safe for cheap.