94 camaro rear end swap

I was wondering what was involved in changing the rear-end in my 94 camaro. It has a 270 open wheel with drum brakes in it now and changing it to a 3:42 posi with disc brakes. I wanted to know what I needed to do co convert it over(proportioning valveor speedometer gears??)  

We did an article back in the April 2008 issue with a Strange S60 and a Moser M9 rear end which was pretty straight forward on what to expect. http://www.gmhightechperformance.com/tech/0804gmhtp_strange_s60_moser_m9_rearends/index.html  

I want to stay with the stock Z28 rear assembly. Is there any changes to the existing braking system that I need to be aware of i.e. proportioning valve etc? I do want to change from drum brakes to disc brakes. I was told by a friend that I need to change the speedo gear top compensate for the gear change. Is this true?  

I thought I read that you could change the speedo with tuning software  

can any one tell me any thing about tuners right now I am trying to get a little power out of my dog chevy pu 06 with a 4.8 would programer be worth wile?   by the way I do have a 72 rally sport camaro on the back burner.