Ok, Just make sure that the roller cam you order has a cast iron gear on it instead of the billet roller cam.
Also are you going to use a Solid roller or a Hyd roller?
If using hyd roller (like I did in my 340 check these links out)
http://www.forabodiesonly.com/mopar/showthread.php?t=131950
http://www.forabodiesonly.com/mopar/showthread.php?t=132009
If using a solid roller (from what I've been told) doesn't have this issue.
I also recommend that you run some roller rockers and use a 1.6 ratio on them, that way you can run a smaller cam and get the same effects as a bigger one.
One last thing is if you are not running a late 80's/early 90's LA roller block, you're going to have to either get the lifter bore bushed and/or run a set of Hughes roller lifters (I have Hughes Hyd roller lifters in my 340, they are great quality) which have the oil ring located futher down and doesn't come out of the lifter bore.