Engine Problems

I have an '87 Accord carbed. The engine has little compression (I believe) because when I press the gas it takes a long time to raise the RPMs. Second there is a loud high pitched noise coming from under the hood, sounds like metal against metal and I don't know what either of these problems could be. I replaced the battery about a week ago to finally get it started, after I did I drove it about 50-100 feet in reverse and drive, but it started dying. I've thought about putting a new engine in it but they are scarse and I'm hoping fixing this one will be cheaper. Any information about the problems, or on where to find a new engine would be VERY appreciated! (Also looking to replace the carb with EFI engine, any insight to that also please!)