The sleeves are larger to begin with on the 400 and the wall thickness would be the same as on the rest ofthe B.B ?...If it aint broke don't fix it ...as for the cold weather blocks as their called the 3rd 1/4 71's are best "440 SOURCE" ...I happen to have one standard bore with about 40,000 on...
sounds 180 out...try puting # 1 dist wire on opposite side of dist directly across from fact #1 then run the firing order n order from there in dist rotation...if its 180 out it will fire up....THEN pull dist after putting the #1 piston on compression stroke "FIRING" and put it back in correct...