X-axis lead screw replacement

Now that I'm more or less caught up on home fix-its since retirement,
I've been re-assembling a Hardinge TM mill. I bought this thing from
Dick Triemstra 5 years ago or so. It was partially disassembled when
I got it. Upon further disassembly for cleaning, it became apparent
that it had led a very neglected life. Everywhere there should have
been oil, there appeared to be a paste made mostly of dirt, with some
grease. Wear on the ways was significant.
Anyway, I cleaned the parts up, stripping the repaint job, which
appeared to be grey house paint applied with an old, much used
warehouse broom right over the old dirt, grease, and spooge. I found
I don't much care for painting, and there it sat until recently. Now
I've finished painting it with grey epoxy (to nowhere near Hardinge
standards) and started the reassembly. So far, the knee, saddle, and
table are back on, with other minor bits. Once cleaned up and oiled,
it's apparent Hardinge built to a high standard. There is very little
lash in the Y and Z axes once I adjusted the nuts. Wear on those two
screws isn't that bad, although the ways are another story.
So now to the x-axis lead screw. It's about 31" long overall, with
16" of 5/8" x 10 tpi acme thread, about a foot of 5/8" shaft through
the handle end, and a short 1/2" dia. section at the end opposite the
handle. In addition, there's about 14" of keyway through the threaded
section for the original power feed. I'm thinking I'll order some
precision screw and round nuts from McMaster along with some shafting,
then assemble the sections with bores, spigots, and silver solder. I
can use the mill with the old screw to cut the keyway, although it's
doubtful I can do it in one setup.
McMaster has 1018 and 4140 materials available. I'm thinking 1018 for
ease of machining for my limited hobby use. Does this sound like the
best choice, and does anyone have other input for me? Thanks.
Pete Keillor