Merc small bore to big bore carb replacement and jetting question

[hollywood120]

If carbs are replaced on a stock 200hp merc from small bore carbs to wh15 big bores is rejetting required to add more fuel with the air or is stock jetting sufficient ? Only thing added is reeds and stuffers at this time! 30cc Heads will be added later i know at that time it will require a step up. Any thoughts on this question. Thanks Frank

[Merc 2.5]

Stock should b fine , wont like to idle if to rich , big bores ain't best idlein carbs neway, more ov a wot carb