55.2-59 Gear ratio and tires size

[Missyblue]

Gear ratio and tire size question.....so my mechanic recommended I get a 28 inch tall tire to go with my automatic 700r4 tranny I'm planning. My rear is a 3.73 posi. But most you guys recommended a 215/70 tire which is only 26.9 inches. It was stated a 75 was too tall but it would put me at 27.7 inches.
I'm planning a highway/daily driver kind of truck. Just curious of thoughts we are currently in the mockup stage so trying to find tire size. According to this gear ratio chart I feel like I would still be within parameters with a 70 series tire. I do like seeing tire haha. Ppanning original type 15 rims. Curious of thoughts
Thanks!