Upgrade/Migrate to PI7.1 from XI3.0

Dear experts

We are planning to upgrade our exitsting XI 3.0 to PI7.1 EHP1. Since PI 7.0 is not supported on 32 bit architecture we have to install PI 7.1 on new hardware and migrate all the existing scenario's from XI 3.0 PI7.1

Has anyone has done this before and is there any details documentation which we can follow while doing this upgrade/migration.

Also I would like to know how to migrate the existing ABAP developements from XI 3.0 to PI 7.1

Any help would be appreciated .

Regards

Pravin