Silver replaces gold as the de facto standard coin. Simply convert all gold piece (gp) prices listed in the packets to silver piece (sp) values. Likewise, copper pieces (cp) replace sp values, and gp values replace platinum piece (pp) values.
Electrum pieces (ep) and platinum pieces (pp) keep their respective values; one ep is equal to five silver pieces, and one pp is equal to 100 silver pieces.
Using this rule in an example: a suit of plate armour now costs 5,000 sp (or 500 gp) instead of 5,000 gp (or 50,000 sp). This silver standard preserves the relevance of copper pieces, and makes finding gold pieces more special. Also, it makes more sense.