29,
I have a couple 6/7 receivers. I like them for the smoothness and the nostalgia. From what I understand, the 6-digit receivers are in demand for the M40 clones. If building a clone is not your thing, shoot it as is or have it rebarreled. My unmolested 6 is going to have a Douglas 6mm 1/9 tube screwed on, chambered in .243 and will be bedded in a McMillan M40 in forest camo with wichita swivels. Pretty classy, i think.
Do what you want and enjoy the rifle. The action is not going to let you retire early- the price's just aren't that high.
David