Chevy 350 bogging after wot?

This is strange feels like its running out of fuel. I rebuilt the engine and used the old fuel pump i've had for 5 years. for the first 3,000 miles had no issue. Blew the trans and pulled it out and had it rebuilt also found a 3.73 posi ands swapped that in from the old 2.56 gears. so got it all in and drove one day all was well. the next day took it out and from 5mph i wot shifted to 2nd and then at 5,000 rpm it bogged still ran but hit a brick wall felt like it ran outta fuel. i shift at 6k btw, full edelbrock performer rpm set heads intake cam 9.5:1 compression. so i bought a new stock replacement fuel pump. no change does the same thing. it seems to happen after about 6 seconds of wot. if im doin 40mph and shift into second she pull pull to 6k then i shift into 3rd and it will bog in third at about 4200rpm. if i wot from 2500rpm in third it will start to bog at 4500ish rpm. this really felt like a fuel issue but why would i have an issue only now? i ran this engine for 30k miles before the rebuild with the old stock pump and have changed to a th350 instead of a t-5 and am running an edelbrock 750cfm now instead of a 650cfm (which is too big but whatever). also have a new distributor cap coil ignition module wires from the new rebuild. am i missing something obvious? ill buy a higher gpm pump if i have to but this just doesnt make sense. i dont have any fuel leaks.