Difference between heads hyd flat vs roller
The big thing is that the roller lifters are taller. This changes the angle of the pushrods going through the heads and will bind and scrape in the tubes of the heads. Edelbrock makes heads with that clearance. At least this is the case with the LA heads. I had to modify mine. I was too cheap to by new made for roller cams. You have to be careful not to cut into the intake runners.
