How To Copy Module Data To Project with Different Customization???

Hello,

Currently running ALM 11.50.777

We need to copy ALM module data from an old ALM project that was poorly customized to a newly customized ALM project.

Obstacles

1. The old ALM project and the new ALM project have different customizations (e.g. entity fields and project lists), which will require field mapping.
2. Data already exists in the new ALM project (concerned about ID field overlap). 

Modules to copy from the old ALM project into the new ALM project

•  Requirements
•  Test Plan
•  Test Lab
•  Defects

*Note: All attachments, coverage and linkages must be maintained.

Methods I have researched, but each item has a drawback

1. HP ALM Synchronizer: Only works for Requirements and Defects.
2. Copy/Paste within ALM: Does not map entity fields and does not copy entity linkages.
3. Export/Import using Excel: You lose attachments, coverage and linkages.
4. ALM Libraries/Baselines: Does not work due to project entity differences.
5. OTA API: Very little experience with both the OTA API and Visual Basic code.

Does anyone know of a tool or solution that could help me out?

Thank you!