Conversions to and from pbm and pk format were posted to comp.text.tex and to alt.sources on the 9th of August, 1990 by Angus Duggan. The program is pbmtopk, and there are also at least two patches.
Chris Lewis' psroff package includes a program to go from pk both to the HP LaserJet and to PostScript.
John McClain <ophelp@tamvenus.bitnet> has some conversion programs for various graphics formats to/and from pk files.
A PC program, CAPTURE, turns HPGL files into PK format, US$130 from Micro Programs Inc., 251 Jackson Ave., Syosset, NY 11791 U.S.A.
Metaplot can take pen-plotter files and prouce metafont files. Note: Pat Wilcox is no longer at Ohio State.
Kinch Computer Company sell .pk fonts derived from PostScript fonts. Kinch Computer Co., 501 S. Meadow St.Ithaca, NY 14850 U.S.A. telephone: +1 607 273 0222; fax: +1 607 273 0484