piston/cylinder head question

had a Dart with a 68 340,headers,484 DC cam,LD-340 with 3310,3.23 gears and 4-spd. car ran 13.18 @108 with 7 X 27" cheater slicks.I could not shift, never used 4th gear, valve guides were sloppy because the heads had been surfaced and I never checked clearances. SO, now, I would like to replicate this combo using a 360. ? is,do I use pop-up pistons with the 587 open chamber heads OR use flat-top pistons with a smaller chamber? I see where the flat-top set-up would probably be better, but my 1st 340 Dart had old TRW pop-ups and also ran 108 in the 1/4...but only had power in 1st and 2nd because the fuel system was not up to snuff. this is more of a what would it have done as anything else. wanna run pump gas only, not E85,yet. and since I'm not gettin any younger...whatcha all think? Thanks! Bob