If you're serious about more HP all ya need is a Stratostreak Pontiac in your Jeep.........
I had 2, 60s Wagoneers with 389s and my Jeep wrecker had a 455.
I don't have any pics of the Wagoneers, but I do have one of my J4000 wrecker/snowplow.
If I could find a decent YJ. or a TJ I would build another Jeep with a 350/400 in it with a 4L80E.