That is what I was wondering about. I see the lifter bores are not only taller for the roller lifters but they also have extra Beef added around the top for more side stress strength for the taller standing roller lifter.
Oh well, fun to think about anyway. I would think a slow turning torquey engine would be fine with a flat tappet hydraulic cam. Can use the simple good working mopar valve train too.
11:1 cr hydraulic 340 cammed '72 340 with factory valve train. This will have some torque, lol . . Ran out real nice on the engine run stand, although a good amount of money was spent on parts and machine work. Simple layout in the end.
I would think the roller cam setups would be more for a high rpm engine.