Just a quick followup to this discussion. Per the suggestion that was
posted here earlier, (and many thanks to Pp for the advice), I emailed
winexpert's tech support and I must say I was *very* impressed - the
person that answered my email was quick to respond, very knowledgable,
and answered all my follow up emails promptly. Kudo's to winexpert and
any other company that understands the value of customer support. I'll
be a winexpert customer for a long time.

Fermentation of my port kit has now finished. I've blended the port
with some brandy - which effectively lowered the SG to a more
reasonable level, while raising the ABV to a level more in line with
commercial ports. The result tastes very promising. I'll post again
in six months or so to let everybody know the results.