More than five years ago I had a thread(since closed) called N-C's Really Agree With Much Of Calvinism. I went through some contents of the 32 chapters of the Westminster Confession of Fath. Allan,a non-Cal agreed with much of what I posted from the WCoF. It is possible for a non-Cal after dithering and being in a nasty mood to finally examine things and exclaim"I did't know I was in agreement with a Calvinistic document!"
Of course the 1689 Baptist Confession (otherwise known as the London Confession)would bring the percentages up even more with a common consensus.
I another thread from the past I had spoken of the Golden Booklet of the Christian Life. It originally was apart of The Institutes. I dare to say that a non-Calvinist would agree with 90% of it at the very least providing they are indeed regenerate folks.
The reason they would agree with much of the content in the 1689 Second London Baptist Confession of Faith is because most of those things are not in dispute. It is God's will of decree, election, and probably the Sabbath (Lord's Day) that are the lightening rod chapters.