I had a sm465 prior to the nv4500..I wanted to keep my 4.10 gears and needed the overdrive..my crossmember is at the rear of the trans..the adapter plates put the ls engine in the same place the smallblock was..love the nv..no problems with aa pressure plate or clutch..I looked into using gm parts to do it but I was having difficulty finding everything needed so I went with the adavance adapter kit. Got a bench seat and shifter clears it fine..headers are a nightmare if you've got a z-bar..I wound up using headers for a hummer and had to do a good bit of modifying to make them work..the problem was finding a set that dropped straight down on the drivers side and then turned back..there are headers out there that claim they'll work with a z-bar but don't be fooled..I think these are the adapter plates I used..
http://www.ebay.com/itm/LS1-Conversi...hT29bU&vxp=mtr