Do I have to upgrade transmissions?

[1994chevy]

Hey guys I'm new to the site and the ls world. I just bought a 04 swb Chevy with the 4.8. I am planning on installing a cam long tubes, etc. I was wondering if I need to get transmission work done or do a swap on it to hold up to the power? And I was also wanting to lower the rear end to sit level with the front, do I just get 2" drop shackles? Gonna need tires soon too. It has factory 17s what size do you recommend? I figure a little wider than factory would look good just don't want an expensive tire