I had an 8 bld warp and took 2 of the blds out (oppositte of each other) this makes a BOW TIE 6 bld. I LOVED it. Dick Hoffman used to run bow ties.
I think a 4 bld is a little under proped for a 200 4 cyl, I had a 68" 5 bld and it worked great on my 200 lyc. 4 blade will work especially if it is longer than 68"
Got run what you got sometimes