4027596 318 head questions??? Help

Im building a 68 cuda notch. I have been collecting parts to do a 318 mild build. I have all edelbrock parts such as a 600 cfm carb. 4 bbl intake non egr. Timing chain,cam, lifters (which i cant use cuz i purchased the flat tapped cam n lifters), valve springs. Ect. I was told the 318 i have was a 77 block. But it turns out its a 89 magnum. With roller rockers and flat top pistons. Question is i purchased a set of 4027596 318 heads. To put on the motor. The only difference i see is between the 714 heads are the holes where the push rods go through look bigger on the 89 motor? Is this a prob? Will the 596 heads work on this motor, any help will be appreciated.