DO NOT expect 340rwhp with full accessories.
It can be done, not hard at all
AFR 185's would work well if you got aftermarket pistons, but if not the TW's or AFR's 165's. Either of those heads will flow enough for 300-350rwhp.
Let your cam grinder know what you want and what you are willing to give up to get it.
Grn had a tfs combo. 304rwhp. Seems like another dime a dozen 300rwhp car, like his stroker engine which is another basic 347. If you want the dime a dozen power, talk to him!
I wouldn't call my stroker dime a dozen as compared to the typical 330-350hp stuff we see daily. Mine will out power those. But thanks for jumping on my dick as you usually do with out offering anything useful. We can call your over priced 300hp set up dime a dozen.
If it was me, I'd go with AFR 185's (aftermarket pistons of course), Holley Systemax, 1 5/8 Longtubes, 65 or 70mm TB (Accufab or Holley for most flow). Custom cam ground to what you want.
Get a 75mm TB if you plan on boost later like you said, otherwise that size is not needed for an N/A engine like a h/c/i 302. Many suggest that because they do not know where the boundry is to make power and how much air there engine can use/needs.
Good Luck, sounds like a fun project!