With the stock manifold, there are two choices and neither of them are what you would consider bolt on. The first is the Weber and the second is the Holley 2300 series 350 and 500 cfm carb. The Holley needs an adapter plate for it to bolt on. Here is what I have heard (I still have the Carter myself and hate it)If you want something just to slap on there and go then Holley is for you. If you like dinking around with your carb and a finer adjustment curve then the Weber is your choice. I am still debating which of the two is better for me as well, or there is always fuel injection, but at a grand it is a bit much for me right now. Hope this helps
The Weber IS a bolt on, the adapter plate just goes right beneath the carb. If you are working slow, the install, including dialing in the mixture and idle, should take you about an hour, that's what it took me when I put mine on a couple years ago.
Brad (from the 4 Wheeling center of the universe, 4 corners USA)