tunnel ram

Hello again. Been working on my carbs. 2 holley 600s Added metering blocks to the back. Went with 66 jets on front and 74 in back with no power valve. Problem is since they are inline wanted to use jet extentions in back but they wont let the float drop. Do they make a side hung float for use with jet extentions. Car 60fts in the 1.40s. Do I need them?