Jim Dove on his web site highly recomends adding mallory (sp?) metal to the 428 crank, which allows it to be internally ballanced. Then you can use any non-428 FE flywheel. I personally never liked externally ballance engines, so it sounds like sound advice to me.
http://www.doveengineparts.com/
click "Jim's tool box"
then click "insites into the Ford FE"
then scroll down to item #4.
Most everything in Jim's tool box is interesting to read.