Choosing the best 5.7 engine and Transmission

Hey guys, I have been reading through all of the gen 3 hemi posts I can but need some help making a few choices... I got my 74 Scamp gutted and I've been collecting parts to start getting it back together. Was a 318 727 car. My goal is to build a fun daily driver. Will likely only see some highway miles, and more just around town and road course only a couple times a year.
My last DD was a 2009 Challenger R/T. Pretty fun car, but my goal is to build something much lighter with a little more power.
I am looking for guidance on which Engine and Transmission to run.
I am planning to pick up a junkyard 5.7 (or hopefully a complete car I can pull everything from) and doing at least a cam swap. Want to be in the ball park of 425 hp & tq.

For the engine, what year and model car/truck should I be looking for? Have I understood correctly that the earlier ones are easier to work with, but are more prone to issues. Then the 09+ have more to deal with electronically but the eagle heads are a big improvement.

Then I am wondering what transmission to go with. Seems like if i am using hotwire already, then using a nag1 or 5454rfe would be the way to go if I am willing to tackle the tunnel and cross member. I have read mixed reviews on which one of these would be better for what i am trying to do.
I am assuming that if I just keep it simple and just run a 727/904 I will be wishing I did the extra work for either one of the newer transmissions.
Not totally opposed to the a518/a500 but if i am going to do an overdrive swap, I'd like to use the shifter and slap stick from the donor car.

Thanks in advance for all the help and input!