engine swap

[69shortcst]

Hey, just wondering if anyone could help me with some advice. I've looked at some member rides and builds and wondering about the LS swaps. I've got a 69 cst-10 2wd short-box and was going to update the motor to make it more driveable (I was running a big block at about 5 mpg). I bought a 1999 Silverado with a 4.8L and will be using it. My question is this...What mounts work without headaches, and do I need to change the pan. I've seen lots of mounts and adapters out there but there is usually one that is better than others, I forget the manufacturer but was leaning towards the kit that includes plates, mounts and tubular brackets. Also i've seen the adapters that move the motor forward or back, is that just to avoid pan clearance problems? Thanks in advance for your help.