Are you just planning on it being a show truck/trailer queen? Or do you want to be able to legally drive it?
Personally, I would stick with the Toyota motor. Get a chrome intake pack like
this:Get a Doug Thorley header, they're nickel plated an look pretty nice, and chrome out your pulleys and other stuff.
You can get a chrome valve cover too.And even chrome oil filters. Personally I like the Toyota motors. And you would have to cut into that smooth ass firewall to fit a 350.