There are several companies selling engine-mount kits for this swap, but it all boils down to a couple of different styles. The weld-in style is flexible, so you can add any combination of engine/transmission you'd like by simply bolting the mounts to the engine, lowering it onto the crossmember, and tack-welding it in place. It's perfect for fitting this combo in a street rod or something with a custom chassis. The other way is to relocate the stock engine mounts on the block using an adapter plate. It puts the engine in the stock small-block location using the original engine perches, helping parts from other aftermarket companies such as headers, modified F-body oil pans, and transmissions bolt right in. The engine adapter we used was from Hooker Headers. It cleared the firewall and all the stock El Camino bits with no problems.>>>
This is the other kind of engine mount offered by BRP. We test-fitted it into the '64 and found that we could move the engine anywhere we wanted under the hood. If we'd gone for a wacky six-speed or an altered firewall, we would have used these.>>>
Accessory Drives
The accessory drive has always been a deal-breaker for this swap. The problem is that the accessories, such as the power steering and A/C compressor, sit low on these engines, and on the '64-'72 Chevelle/El Camino, they interfere with the crossmember and steering box. So when you score that killer LS1 off of eBay for $3,000, you get stuck with that accessory drive.
 The S&P kit comes with an...  The S&P kit comes with an alternator and an extremely small power-steering pump with an external reservoir for this application. The company also has a kit for virtually any other car already scienced-out. |  Since the instructions are...  Since the instructions are just a photocopy of a photo of the system, you'll need to know that the pump must go on first. Other than that, it takes five minutes with an Allen wrench set. |  We chose the simplest system...  We chose the simplest system to save time and money, but if you want, you can add A/C. It adds significant cost to the system, and on the '64 El Camino it requires notching the crossmember on the passenger side. |
One option is using a truck accessory drive. It's ugly, but it's the cheapest way we've seen to get everything on the engine. The downside is that both the alternator and the power-steering pump are placed high on the driver side of the engine and will interfere with the stock throttle body on an LS1 intake. So you either swap to a truck EFI intake, swap to a carbureted intake (which is a whole other story), or modify the idler pulley location and bend the outlet on the water pump to 90 degrees to clear the belt. We've seen this mod performed by the guys at Speartech Fuel Injection Systems. It's pretty hard-core. Also, the truck crank pulley is longer than the F-body and Y-body pulleys, moving everything closer to the radiator.
Most of the engines we've seen in the wrecking yard and online have a 4L60E hanging on them for just a few dollars more. Nearly all the companies we talked to assumed that's what you'll use. And why not? The 4L60E has a 3.06:1 First gear and a 0.70:1 Overdrive. If you are using a transmission sourced from the classifieds or somewhere else, check the number of pins on the large gray wiring harness connector. If it has 13 pins, you can use it for this swap. If it has 12 or even 15, you'll need a different flexplate to get it to correctly bolt to the torque converter. If you don't get the engine and the transmission as one package or you are using parts sourced from different places like we are, you can buy a complete kit from Keisler. The company calls it the A 41. It's essentially a 4L60E that has been rebuilt and upgraded to handle 450 to 650 lb-ft of torque, prepped for an electronic speed output, and is fully programmable. It even comes with a crossmember, a driveshaft, cooler lines, a shift linkage, and a lockup torque converter, and you can use it behind virtually any GM engine-fuel-injected or not.>>>
The next best thing is to use the Corvette (Y-body) pulleys. We've seen them new for $600 on eBay, but that doesn't include the alternator or power-steering pump, and good ones will cost about $600 more from places like Rock Auto online. The Y-body system puts the alternator and power-steering pump up on the driver side in a less grotesque fashion than the truck pulleys, but we've been told by Mark Campbell at S&P that the Vette power-steering pulley can hit the upper A-arm on the Chevelle/El Camino.