Archie's LS kits are Manual transmission only and will not work with an automatic. The reason is his manual kits are designed to use the stock 168 tooth flywheel that comes on the RWD engine. This flywheel is about 14" in diameter and places the ring gear very close to the axle centerline. There is no way to fit a 168 tooth ring gear alongside the 4T65e-hd... the transmission case is in the way. The only ring gear that fits is the 142 tooth one.
You will need to do what Don Kraus did for his LS 427 build. Start with an LS4 4T65E-HD as it has a transmission mounted starter placed for use with a 142 tooth ring gear. His build thread is here:
https://www.fiero.nl/forum/Forum3/HTML/000083.html
You will need a flex plate, and before you just plan to use the LS4 flex plate, it has a 6 bolt pattern and the LS7 has an 8 bolt pattern. Plus Don ended up upgrading his flexplate to a heavier one anyway, so you are probably looking at a custom piece.
You will need an adapter plate. Don used a Fast Fieros adapter plate but it is on longer available (and Don had issues with it anyway).
You might PM Don to get the adapter thickness and then call up Street Dreams by Ross and compare the thickness to their SBC Fiero adapter plates. They are close in thickness, but I don't know if they are "close enough". The SBC and LS(x) engine share the same bellhousing pattern and dowel pin locations, but the LS(x) doesn't use one hole. If the Street Dreams plate is the right thickness, then use it to mate the engine to the 4T65E-HD. You will need to cut off the Street Dreams starter plate and mill a slot for starter mount clearance as the starter hangs past the bellhousing face of the transmission.
For the accessory drive, I would recommend using the LS4 accessory drive (like Don did) as it keeps the belt drive as close to the engine as possible. You might also be able to use Archies LS accessory drive, but you would need to verify the side to side mounting positions between a LS4/4T65e-hd and Archie's LS(x) installs. Archie has done both, so he could possibly tell you if his LS(x) accessory drive and water pump could work.
Once that is done, then I would suggest you run the Doug Thorley headers for the LS4. You can modify them like Darth Fiero did in this picture.
Before you go down this path, you really should consider if you want to do this to a legitimate LS7. For the engine to clear the 4T65e-HD, you will have to cut the starter pad corner off the block by a significant amount for transmission to nestle up along side the engine. This will ruin the block for ever being used in a RWD configuration for 90+% of the people.
The other transmission choice with unverified strength and not much aftermarket performance parts is the new 6 speed auto (6T75). It stays on the bellhousing side of the engine and might allow you to avoid cutting up an LS7 block. You will still need an adapter plate and must fabricate a starter mount on the transmission and the Thorley headers might no longer fit, but it would possibly keep you from permanently modifying the LS7 block.
https://www.fiero.nl/forum/Forum3/HTML/000136.html[This message has been edited by fieroguru (edited 04-06-2014).]
