73 dart hemi swap help

So I'm extremely new to mopar. Just bought my first mopar 2 weeks ago and I want to do a hemi swap on it. I've done lsx swaps into old chevy's and all that just never really dabbled much into mopar because I've always seen Chevy as cheaper and easier because that's what I grew up on. I just need some basic information on the swap from someone that has done it.

First, will I need to swap the k member from an origional slant 6 dart?
Will a 5.7 hemi out of a truck fit under the stock hood or should I go with a motor out of a magnum or charger?
Will the stock 904 transmission and rear end hold up to the power as long as I don't stomp on it?
Will there be any major clearance issues? (Fender wells, power steering, heater etc)


I know this is a big task for someone new to mopar and I don't mean to sound snotty but I don't need a bunch of people telling me that.

The reason I'm doing this swap is because I'm going to be driving from San Diego to Chicago in 7 months and I feel like the stock slant 6 Will have a ton of trouble making it over the mountains. And I don't want any problems. Also its a decent start to the future of the car