Is 3.08 to low to use 4th gear around Town?

[Boog]

I had an 88 with 305/R4 with 2.73 gear and 29" tall tires. Yes the 305 was a real noodle for power but with the low cruise rpms it had a terrible time staying in od at 70 mph. The slightest incline or headwind forced it to downshift into 3rd. Consequently it didn't get great mpg either.
The small blocks sweet spot as I've come to call it is normally between 1800 and 2200 rpm. They are more efficient in that range.
As said you have the option of using 3rd gear instead of od. It's the same as these trucks came with back then. 3.08 is a good all around gear for a non od application.
A 3.42 or better yet a 3.73 gear works great with an od trans and 28 or 29" tall tires. You get better pulling power and od to bring the rpms back down at cruise speeds.
Figure out how you intend to mainly use the truck and tune it for that. Low speed around town use or mainly highway.