This is where I'm at with mine as of now. Hopefully the rest of my still will be here today
You'll need:
Upper
Lower
Lower parts kit
Bolt carrier group
Charge handle
Buffer tube, spring and buffer
Butt stock
If your upper is stripped, you need an upper parts kit
Barrel
Gas block
Gas tube
Hand guard
If barrel is threaded you need a thread protector or muzzle device.
I'll have about 800 into mine
Look on eBay for a lot of parts. Joebobsoutfitters for stuff and vtsupply.com for stuff
You dot. Need mega upper lower kits or spikes or special. If stay away from polymer personally.
Andersonson or are I are good lowers. Uppers are usually 100 bucks same as lowers.