700R4 trans leak

my 70 chevelle has a older model 700R4 trans sitting behind a 454. trans yoke is slinging oil on floor pan and cross member. trans had a rebuild last summer, new yoke seal installed. seal and yoke look dry and hole in yoke welded up. is yoke shot? also have 410 rear with 17 by 29inch tires and speedo is out of sight, did put 45 tooth gear in, would i have change other gear in trans? need all the help i can get , thanks