I've given up on making this in hardware and am developing a web page instead.
I have a Perl script to convert the data tables from VSOP87 ftp://ftp.imcce.fr/pub/ephem/planets/vsop87 and described in
The coefficient tables used by the website are derived from
Planetary" class="redactor-linkify-object">http://adsabs.harvard.edu/full/1988A%26A...202..309B">Planetary theories in rectangular and spherical variables-VSOP 87 solutions by
Pierre Bretagnon, Pierre, and Gérard Francou and published in
Astronomy and Astrophysics, vol. 202, Aug. 1988, p. 309-315.