360 or 440?

I am in the decission making process for my 71 Swinger build. the question i have is this. Should i go with a 360 or 440? the body is a 318 car by VIN number but it seams that some time over the life of the car it MAY have been changed at one time. the mounts on the K member look as if they have been welded on by some one not a pro. the car will be used on the street as a driver, not the track. although i want it to be quick. I have a 360 with trans out of a 85 truck. i know that i need to change a few things on the motor for it to fit and the body should take it easy. I also know where there is a truck that some one told me has the 440 with trans and price is $500 for the whole truck. How much would i need to change to put the 440 in the car. like i said it will be a driver so I would like to keep power steering. body has disc brakes but not power. So for a mild street car would it be worth the hassle of putting a 440? So any input would help me figure out what the hell to do. thanks guys and girls.
Jeff