PiTR and other architectures....

Having just tried to restore a 64 bit BSD database to a 32 bit linux
machine (using PiTR), I have now realized the (with hindsight, obvious)
error in my ways.

Now, I need to plan a way forward. From reading of other peoples similar
problems, I now realize that I need a system with identical on-disk
formats. Question is:

Is there a simple way to determine compatibility? (eg. a small
well-defined list of requirements)

In the specific instance I am working with, I'd like to copy from 64 bit
AMD BSD system to a 64 bit Linux system.

Philip Warner