1967 Barracuda Slant Six to 440?

OK, so I have a '67 Barracuda, 9 inch drums all around and the gas mileage on my Slant isn't as good as I wish it could be. I figure if my gas mileage isn't great I might as well throw a V8 in it and have fun at the same time.

Anyway, for $400 bucks, my buddy will sell me a 440 engine and transmission out of a 70's motor home. Runs good. Tranny works.

What other mods would I have to do to my car?
I figured new rear end, front end parts and disc brakes. I know many of these parts are available from later year vehicles.

I have also seen tube chassis front end disc conversion kits with rack and pinions and things of the sort made by MP and other companies. Are these any good?

Thanks, any input is appreciated.