Idp v3 fresh install but reuse old certs and metadata etc

[C G]

Yes,  upgrade from existing  v2 to v3 would have been a choice, but we 
Had some integration work and to make sure all is working with v3 with integration/customization. 

Appreciate any pointers to my Q. 

Have an old v2 idp working. Have a few SPs external configured and pointing to this v2 idp. 
We have a fresh install and customized v3. Would like to reuse v2 certs, metadata and anything that can 
Be reused so we have no change on those SPs. 

Can someone point me to step by step on reuse of major elements from v2 for v3? 

Thanks in advance!

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