{"coordinateScale":450.0,"heightScale":1.0,"lowerLimitScale":1450.0,"upperLimitScale":1450.0,"depthNoiseScaleX":200.0,"depthNoiseScaleZ":200.0,"depthNoiseScaleExponent":0.5,"mainNoiseScaleX":1800.0,"mainNoiseScaleY":5000.0,"mainNoiseScaleZ":1800.0,"baseSize":12.25,"stretchY":4.75,"biomeDepthWeight":1.11,"biomeDepthOffset":0.01,"biomeScaleWeight":4.0,"biomeScaleOffset":0.01,"seaLevel":80,"useCaves":true,"useDungeons":true,"dungeonChance":100,"useStrongholds":true,"useVillages":true,"useMineShafts":true,"useTemples":true,"useMonuments":true,"useMansions":true,"useRavines":true,"useWaterLakes":true,"waterLakeChance":4,"useLavaLakes":true,"lavaLakeChance":40,"useLavaOceans":false,"fixedBiome":-1,"biomeSize":5,"riverSize":5,"dirtSize":33,"dirtCount":10,"dirtMinHeight":1,"dirtMaxHeight":256,"gravelSize":50,"gravelCount":10,"gravelMinHeight":1,"gravelMaxHeight":256,"graniteSize":50,"graniteCount":40,"graniteMinHeight":1,"graniteMaxHeight":192,"dioriteSize":50,"dioriteCount":40,"dioriteMinHeight":1,"dioriteMaxHeight":192,"andesiteSize":50,"andesiteCount":40,"andesiteMinHeight":1,"andesiteMaxHeight":192,"coalSize":26,"coalCount":20,"coalMinHeight":1,"coalMaxHeight":256,"ironSize":17,"ironCount":20,"ironMinHeight":1,"ironMaxHeight":192,"goldSize":13,"goldCount":2,"goldMinHeight":1,"goldMaxHeight":48,"redstoneSize":10,"redstoneCount":8,"redstoneMinHeight":1,"redstoneMaxHeight":24,"diamondSize":8,"diamondCount":1,"diamondMinHeight":1,"diamondMaxHeight":16,"lapisSize":10,"lapisCount":1,"lapisCenterHeight":24,"lapisSpread":24}

I did a post-world-spawn change of coal size of 24 (slightly smaller) and iron size 20 (slightly bigger)  Areas far from the spawn will reflect this new change.  Full Preset string below:
{"coordinateScale":450.0,"heightScale":1.0,"lowerLimitScale":1450.0,"upperLimitScale":1450.0,"depthNoiseScaleX":200.0,"depthNoiseScaleZ":200.0,"depthNoiseScaleExponent":0.5,"mainNoiseScaleX":1800.0,"mainNoiseScaleY":5000.0,"mainNoiseScaleZ":1800.0,"baseSize":12.25,"stretchY":4.75,"biomeDepthWeight":1.11,"biomeDepthOffset":0.01,"biomeScaleWeight":4.0,"biomeScaleOffset":0.01,"seaLevel":80,"useCaves":true,"useDungeons":true,"dungeonChance":100,"useStrongholds":true,"useVillages":true,"useMineShafts":true,"useTemples":true,"useMonuments":true,"useMansions":true,"useRavines":true,"useWaterLakes":true,"waterLakeChance":4,"useLavaLakes":true,"lavaLakeChance":40,"useLavaOceans":false,"fixedBiome":-1,"biomeSize":5,"riverSize":5,"dirtSize":33,"dirtCount":10,"dirtMinHeight":1,"dirtMaxHeight":256,"gravelSize":50,"gravelCount":10,"gravelMinHeight":1,"gravelMaxHeight":256,"graniteSize":50,"graniteCount":40,"graniteMinHeight":1,"graniteMaxHeight":192,"dioriteSize":50,"dioriteCount":40,"dioriteMinHeight":1,"dioriteMaxHeight":192,"andesiteSize":50,"andesiteCount":40,"andesiteMinHeight":1,"andesiteMaxHeight":192,"coalSize":24,"coalCount":20,"coalMinHeight":1,"coalMaxHeight":256,"ironSize":20,"ironCount":20,"ironMinHeight":1,"ironMaxHeight":192,"goldSize":13,"goldCount":2,"goldMinHeight":1,"goldMaxHeight":48,"redstoneSize":10,"redstoneCount":8,"redstoneMinHeight":1,"redstoneMaxHeight":24,"diamondSize":8,"diamondCount":1,"diamondMinHeight":1,"diamondMaxHeight":16,"lapisSize":10,"lapisCount":1,"lapisCenterHeight":24,"lapisSpread":24}