Distance from rear of block to front of water pump (without spacer for fan) is approx 30.5" if its a 200, 32.5" if its a 250.
The real problem is that the 250 is a lot taller and has a huge flange at the back which holds a huge 157 or 164 tooth 14" flywheel, and the water pump has to jutt out more.
The early 200's run 132 or 136 tooth flywheels, and are much easier to fit within the engine bay. The last big bell 200's ran a 164 tooth 14" flexplate, so its hard to fit.
It will not fit without a 3" rebate in the fire wall, and extra work on the front radiator support.