I read a ton of stuff on this today. Here's how I understand it.
The rules are very, very clear and there is a ton of room for interpretation.
Basically hire a trustworthy RI and let them do what they do.
And it's perfectly acceptable to swap an engine for an unapproved one - at your own risk...
Clear as mud.
2011 LR4 Metropolis (white)
2003 DII Santorini Black (I think)
1981 FJ 40 Beige
Defender - in the market