Trade silver bullion for gold bullion (Perth Mint) at GSR. [Photos now included]

Looking for expressions of interest in trading about 30kg-55kg of silver bullion for equivalent in gold bullion (for easier transport, as Perth has just lost its only independent storage vault - so the stack has to be transported or stored at home - but i sold my property since i bought my stack so dont have my own property to store it at anymore.
It's all Perth Mint bullion - purchased 2009 (so probably 2008 or 2009 cast).
99.9% grade.
20oz bars (about 40-80), and 10oz bars (about 20)

Would be most interested in trading for Perth Mint gold bars (99.99%) - preferably 1oz bars, possibly 1/2 oz bars, possibly some other denominations - eg. 10 gram to 50 gram gold bars.
Re price - i think straight up GSR - Gold/Silver ratio (ratio of Ag and Au spot price - eg. as displayed on Perth Mint website).

The timing is good for this trade as the ratio is historically high - ie. silver is lower than it should be - has more upside potential. But for international transportability, silver is a real drag.