I say keep it Olds because of what it is. Since you got the engine running, you can still easily do the swap with no mods. One thing I recommend is doing the swap with an Olds small block and save the 307. If you ever decide to put the 307 back in, it will be no trouble putting it back in. You can set the computer harness to the side and the new engine will go right in. Even if you dont like fixing things that are not broke, you can easily make it better.