The cam journal is the same in all the small block engines. So swaping in a cam doesn't have pitfalls of "What year do I have?" type problems or fireing order & counter rotation problems.
So yes, it is feasible.
On the problem of lifters, the style of lifter is also what style of cam you have/want. The Magnum engine uses roller lifters stock but can be re-equiped with a Hyd. or solid cam with the like lifters. You can not swap lifters around from cam to cam, or Hyd. cam to mech. cam to roller cam.
Trust me, it just won't work. The cams are ground to work with the lifters that are gound to work with that style cam.
The great thing could be that if you have a full roller engine now, the price of the cam is all your going to payout unlike if you just have a bare block and then need the lifters and everything else on top of it.
Just beaware if the roller cam needs a bronze distributor gear drive or not.