That was enough info to get me close. A Google search turned up these two links which are key to making this work.
https://www.x.com/developers/paypal/documentation-tools/paypal-payments-standard/integration-guide/Appx_websitestandard_htmlvariables#id08A6HH0D0TA
https://www.x.com/developers/paypal/documentation-tools/paypal-payments-standard/integration-guide/Appx_websitestandard_htmlvariables#id08A6HI0J0VU
You have to included address_override = 1 in order to actually pass the address to Google. The reference material says that adding this variable will prevent the user from changing the address you passed, which it does, but without it, the address is not passed at all.
I would like to suggest that you add address_override to eCart in a future update.