The plenum in the bigger restriction, replacing that, alone with the stock tb will net bigger gains that replacing the tb alone.
Accufab is a favorite of many and has almost all great reviews (70 or 75mm). This is the priciest combo. (2 piece, polished)
Trick flow offers an inexpensive option that seems to go over well, but every post i have read, has indicated that you will need to modify the throttle linkedge to get the cable to fit properly. SVE (late models house brand). Looks to be the exact same as the trick flow. Also 70 or 75mm. (2 piece), sve only in machine finish, TF in machine or black powder coat finish).
I have the SR 70mm single piece polished piece and am very pleased with price, performance, and finish. (polished or black powder coat).
Most run a 75mm. A few on here have complained about mildly modded or stock engines bogging a bit on 75mm, most have no complaints.
I assume you are wanting 350-400 engine hp and not rear wheel. Honestly from what i have researched so far that will take a 2v a little more than you may be thinking. Here is what i suggest.
1) talk to stevew01. His na motor build has him in the 400hp range +/-, before his no2.
2). Consider a blower. What ever your flavor (twin screw, roots, vortec/paxton). Our engines do well blown and i think you would be there all day long.
3). The full bolt on route..(full exhaust with long tubes, ud pullies, cai, tb/plenum, and tune). With stock heads/cams. Will wind you more in the 320 +/- engine hp range.
Thats my 2cents.