Before I started using the GUESS reports and equations, I tried to do what you are talking about....but just using NON-weighted cores. It was better than nothing, but not as good as weighted cores.
Since then, I have made some modifications to some GUESS formulas, but have not attempted to do this "baseline" thing. I have established "minimums" that I look for in recruits and that separates the men from the boys, then I just try to get the best guy that meets my minimums.