A friend of a friend slapped a 390FE into a 4 banger hatch. It was a total hackjob though. Motor was up way high, and tolted so the C6 would fit in the tranny tunnel. It went pretty good, and the welded 7.5" held up for a long time. Although he had cooling issues with the 4 banger rad and electric fan (duh). It once got so hot that the casing melted right off the sparkplug wires, wouldn't shutoff untill he pinched off the fuel line
I have a clip of it after he put a cowl to clear the carb and painted it nice. It looked good on the outside, but a chain wrapped around the driver's exhaust manifold down to the chassis was not my idea of well built.
I have a video clip that im putting up on google video as we speak, but it will probably take a day or so to get approved.
My take, if you have the motor, it can work, but there are a lot better choices (stroked windsors or 385 series motors).