Thanks for the replies so for, you're right about my knowledge level which is why I'm asking advice on the forum.
The M20 appeals as it was done by LR themselves on the M50 engineed SA spec defender but as you say, I'm thinking despite it's advanages it will be a much more difficult project and do the benefits over the V8 warrant it?
I was thinking of giving Ashcrofts a call but never having dealt with them and being new to LR ownership I wasn't sure how open they are to a chat of that nature. I'll give them a bell.
Thanks.