Cracked Flex Plate

Hi, I'm new to the forum. I have a 1969 Dart, 340, 727, that started making a racket underneath. I was able to crawl underneath and look at the flex plate and it is cracked. I thought that was the only problem, so I pulled the tranny and replaced the flex plate, along with the converter, along with a new front seal. Now, I have delayed engagement when going from park to any gear. Once I rev the engine it is fine and there are no other problems. I did not have to do this before. I did drain and replace all the ATF as part of this, and the dipstick reads full on a hot engine while in neutral. It appears to me that the front pump may have also been damaged and I wasted my time just replacing the flex plate, converter and seal? If it is the pump, what else do I need to replace so I don't do this again? The tranny has about 2000 miles on it after a rebuild.