LS1 Conversion--> Tips, Tricks, Tuning?

I am interested in selling my 350 w/144 blower and doing an LS1 conversion in my 56. I'm brand new to the LS1.

I've read a little about needing to either purchase a new computer, or harness; or have it programmed to turn off things and turn on things, etc.

Would purchase of HP Tuners, and other components, along with some research, provide me the capability to save purchase of a new computer or harness?

If so, can anyone direct me to information on what I shoudl plan on programming? Maybe a 'How to'.

Also, as that I have not purchased an engine yet, any feedback on what I should look for, or steer clear of? Particular add-ons I should consider?

My current 350 has a built 700R4 behind it. I'm told I should sell that too, and put in the auto that comes with the LS1.

My goal: have a very streetable, decent performing, good looking engine in my 56 Kruiser.

Any suggestions and feedback appreciated.