Cheapest way to change ratios on an 8-3/4, and what ratio to choose?

get another open chunk with gears you need (SWAP PIGS AS NEEDED)
i have FOR SALE
741 case 3.23 gear chunk
489 case 3.23 gear chunk
742 case 2.76 gear chunk

i'm a good trip away though, but you may be able to find fabo members closer to ya that can sell ya one.