How much more block clearancing do you need on a 396 versus a 383?

 

If you are referring to main and cam bearings- the specs should stay the same...
most everything stays the same...

 

I'm pretty sure he's talking about clearance because of the extra stroke.
You'll have to take a little more material off in some areas. There's not any real way to know for sure until you get it all together and find out where it's close. How much you take off also depends on the parts you're using (i.e. H-beam vs. I-beam, etc.).

 

Well, assuming that you use the same rods on each motor, I'd say that a 3.875" stroke takes about 0.0625" more clearance than a 3.75" stroke. What's heavily dependent on the rod is whether this extra 1/16" of an inch will cause problems with the oil pan rail, cylinder base, or camshaft. Needless to say, "profiled" stroker rods are the way to go if you intend to run a standard base circle cam and don't want to run the risk of cutting into the water jacket.