use 400 rods in a 383

[ron 52]

Is there a good reason not to use 400 rods when building a 383 ?

[73RS]

THe 400 rods are shorter than the 350 rods, 400 5.565 if I remember right and the 350 are 5.7. The shorter 400 rods cause a more extreme rod angle which is harder on the cylinder walls and pistons and not good at all for high RPM usage. Not good to turn a motor with those rods over 5000 rpms for very long and the motor won't last as long either due to the greater wear. Know a lot of folks that have thrown a rod in a 400 due to turning the RPM's up above 5000 one two many times. The shorter rod will give a bit more torque due to better intake filling due to a higher piston speed in the top end of the stroke.
I would suggest using the 350 rods when you can, throw them 400 rods away, they ain't good for much. JMO