General Engine swap question.

I'm trying to find the definitive best engine for the Mini and it seems YouTube has different engines being suggested. Which engine is the overall best option for Off-road and I'm also wondering for the Track?

I'm also wondering which V12 do you all suggest for the Audi R8 to turn that into a Chrysler ME-412? Also what V8 would be best for the Chrysler ME-8 like they talk about on 

Hagerty. Media in their what if stories.

 https://www.hagerty.com/media/what-if/what-if-2022-chrysler-me-8/

A lot of my other ideas I'll probably just pick what I want. We all know it's pointless to own anything other than an RSR in this game.