A bit of experimentation...considering the manufacturer/origins/other cars the steelies were used on, figured I'd try other sources, since the usual suspects here on this side don't seem to stock the originals...just the big acorn nuts for panasport pattern wheels...picked up a set of lug nuts from Moss (part 674-625), measured them against the few originals I had left...and they were the same thread and socket size, as well as taper (60 degree). Torqued them to spec (40 Ft/lbs), and have run them on interstate highway, local potholed streets, and some twisties over on the other side of the Taunton River from Fall River (some GREAT roads back in Seekonk and Rehoboth...who'd have thought...we're talking English country lanes...but figures since that's who founded the towns 400 years ago...) for 250 miles+ since I installed them.
Checked the torque this afternoon. Still at 40. Doesn't look like they've started to pull through or otherwise loosen. I think they're good to go. No financial interest, etc. But, an alternate source if yours are missing or knackered and the suspects say the only option is the chrome acorns.