Almost completed AR10 Build - reccomendations on a few more parts

I am almost done building my PSA upper and lower "AR10" build.

I have a PSA BCG, PSA Lower parts kit, PSA buffer, buffer spring, a Magpul PRS Stock.

Only thing I need is the handguard, gas system and barrel.

Handguard will eventually have a bipod mounted on it.

I probably need to wait until I buy the barrel to determine what diamater gas block I need, correct? on a 20" barrel what length gas tube would I need? Are they the same lengths as AR15's (carbine, mid length and rifle)?

I have not done much research on what barrel or handguard I want yet. I have heard good things about this one. Any people have experience with the company or know anything about them? Its sold by Fulton Armory but made by Criterion

http://www.fulton-armory.com/barrelfatitan20nmm110ss1x12875gasblockthreaded.aspx

I did say that... but did not mean it. haha, I must not have been awake.

Scope will be mounted to the upper, bipod mounted to handguard...maybe just maybe a flip up pair of back up sights will be added to the handguard, but likely not.

Definitely going to hide the gas block under the handguard.

No firm price range for the barrel. I found some made by criterion that seemed good and were shockingly only about $390. I read a few good reviews but have found very little reviews on them elsewhere. I am looking into them more.

Handguards - I'll probably stick to a common known brand. I am not looking at anything ridiculously fancy or decorative. Probably key mod or something similar. I don't need or want all that empty rail space for no reason.

I was also looking at the Rainiers. Thanks for the advise.

I also ended up going with the Rainier Arms match grade 20 inch. Unfortunately they didn't have the matte finish or the black banded with stainless still but I don't think that'll be that big of a deal once I get it together and probably end up hiding 15 inches under a long rail

I ordered a 15" JL BIllet handguard. I liked the look alot.