Hey it's your jeep to do what you want with but are you sure about what it is you're aiming for with it? With a small 8 & for road only use you really don't need a 4 speed- you'll never ever use first & you'll hardly ever use second. 70 in an ECJ5 can be done but it's widely considered Not To Be a Good Thing to Do- with the short wheelbase & high center of gravity handling can be squirrely, if running a lift or off-road tuned suspension it gets worser faster. And you'll certainly need a brake upgrade. As stated you will need to change out the steering gear- with a saddle mount engine that could become very involved. If you don't go for the 3 series axles you'll find that the engine RPMs will make for a loud ride, that's ok if you're going short distances but if you're commuting any distance at all it gets old quick Not trying to knock your vision but some of what you seem to be going for just isn't adding up.