68 Charger steering issue

Memory-steer, as you call it, is usually;
lack of caster; and btw; excessive rake steals caster.
or more likely is that the steering box set-up too tight, or
the lower BJs are tight, or
Low tire pressures, or
just general tightness in the steering somewhere.

Jack the car up under the lower control arms, and grab a wheel, and attempt to steer the system left and right. If it is hard thru it's entire travel, yur gonna have to hunt for it. BUT
>If it's notchy on center, check the sector-shaft end-play; you gotta have some thru the center, and up to about an eighth of a turn either way on the steering wheel, which is by turning the steering box input shaft NOT the steering wheel, and with the engine NOT running.
A trick I use is to watch the sector shaft (the one pointing down). On the switch-over from one direction to the other, the sector shaft will rise up into the box ever so slightly, then reverse direction. A couple of thou when hot, is all it needs.
To figure out if the tightness is in the BJs or in the steering your option are to disconnect one of the following; the pitman arm is easy if you have a puller. or the Idler arm if you don't, and let it hang. Or you could drop the two outer tierod ends if you can do it without destroying the rubber boots. But once both the steering arms are hanging, you can easily inspect the ends.
If it turns out to be the BJs, which is where I usually find it, you still gotta figure out which one it is. I usually find it in the Lower one.
AFAIK, a tight LBJ is a throw-away. The cheap off-shore junk is designed that way to last more than a week.
I never was able to physically save a tight one, nor did any different grease fix them up.
When I was an alignment tech, I had to educate my supervisor, that those el-cheepo joints were not saving anybody any money, beyond the day-one savings. But no matter, it took the utter disintegration of one, in a pick-up truck, that folded everything under the truck, destroying all the steering and suspension on that side, plus the sheet metal, and the resulting 60 mile tow; for the boss to get it.
In those days the brands to buy were Moog, TRW, and one other that escapes me now; which never gave me any trouble. But
I heard that both of those went to China after I moved on, with predictable results.
I suppose, you may have to go to your jobber and go thru his inventory to find an acceptably "loose" one.
The junk parts were warrantied by the vendors, but my labor was not. I mean, I told them those parts were junk.
And you know, I had to redo the alignment. Nothing changed, but I had to look, cuz if I didn't and the tire wore out, guess who would get the blame for that! I wasn't having it.