I was just looking in the tiny little mopar performance book that is still left and I was looking at the hemi section and I saw the solid lifters they sell are .005" undersized and I remember doc said the slant six could use some massaging and somewhere else I herd the hemi lifters were the same size so I put 2 & 2 together and I was thinking would this be a short cut to boring out the lifter bores?

I haven't seen a hemi lifter, but you also have to consider height, not just diameter. you might need new pushrod length.

the "cup" may also be of a different cone, leading to a sloppy fit of the pushrods.

just things to consider, but yours is a new idea. without two of them side by side right here next to me I can't really say it would never work.

its probably best to try to attract Doc's attention, then ask him.

well im thinking about ordering one to compare side by side cuz my cost on a mopar performance lifter is only $6.60 ea

Getting a sample is a good ides for the reasons listed above.
From past exp. this lifter will be a match and drop right in. (a .005 undersize easy drop-in)

.005 u/s concerns me a little, I have never run one that loose, I usually shoot for .002 -.003 clearance. I don't see any "show stopping" problems with that amount of looseness, the (cast iron) SL6 lifter bores are thick and solid so you are not going to hurt them.
DD

well in that case I might just take your original advise and massage the lifter bores a little