rear gear change

You can put a taller tire in the rear and change it from 5-10% by increasing 1"or 2" in diameter. That would give you an equivalent to either a 3:90 or 3:69 if you can live with either one of those ratios and the tires fit? Just remember your speedo will read "slow" that much too. You can always buy a boneyard whole stock rearend and swap them out fairly cheap. I like my 3:27 running a 1" dia shorter tire making it a 3:43 ratio.

It's a time consuming specialty doing these right. Here is an example of a whole series on Utube just on rebuilding the 8.8" Ford properly.