Putter "n" sputter

so after the eariler posts...i have got the boat running pretty good...3.0L 181 mercruiser ....full tune up...rebuilt carb...used a Mikes Carburetor kit with a brass float...so one question i have is...with the brass float how/where do set the float level and drop...i was told to use the seam.. but if you set the level to 9/16 you dont get close to the 1 1/32 drop....i know its fairly easy with the plastic float..but the brass one is ??? so i just set the level to 9/16 using the seam and left it at that....any thoughts??....so ran it today.. ran really strong, used to could only get about 42 mph but cracked 46 today....along with the card build set the linkage idle screw (with linkage disconnected) to just touching cam and then 2 full turns and put in a new idle mixture screw...all the way seated and then back out 1 1/4 turn...had to tweak those alittle while running with muffs at the house to get it to idle well....now out on the water i ran great full throttle but at idle after running awhile seemed to surge a tiny bit like in rpm..no body else would probably have even noticed it..but at the helm i did....and then after about an hour of run about...i went to kill the engine and it did like the old carburetor car back in the day it puttered and sputtered for about ten seconds before it finally shut off.....you guys see anything that you would have done different...im sure its back to adjustments...just not sure where to start...thanks

Reset the idle mixture screws to the highest idle speed you can get, then leave them there. Most engines don't like lean, but thrive on rich!

ok...will do thanks