wondering what size 24's i can run on the back of a K5 blazer

[67cheby]

I am just starting some research, i am building my wife a K5 blazer that will lay frame with air ride. My question is if i use the stock rearend what is the biggest 24x ??? 12 ?? i can run on the rear and what kind of offset can i expect without narrowing the rear axle ? I realize that their are alot of variables here just looking for a close idea . I will be cutting out the floor and raising the factory tubz all the way up and reverse tubbing the sides, just wondering if someone can get me close ? I also want to run a back seat (dual buckets) , i dont have a tub yet to look at how this will work but it is possible isnt it ?