8.75 Ratio opinions

I'm with 318willrun in that a taller gear might even be just fine. I have a 68 Cuda FB and it's a heavy pig (3450 empty) and a 408 making about the same power you say yours is and right now I'm running 3:55's with much taller tires than you at 275/60/15 but I'm planning on swapping back to 3:23's that I had in it previously. The 3:55's are great for racing and ok for the street but with 500 lbs ft of torque on hand and a 3K stall or higher there isn't much difference in how quick it is with 3:23's and it runs 250 less rpm down the hwy. If you drive a lot taller gears are your friend too. The 3:23's I had in mine got nearly 2 mpg better than the 3:55's... JMHO