Narrowing Costs

Whats the average costs to have a 9 1/4 diff narrowed? I got one out of a durango, along with the leafs and drum brakes. Planning on narrowing it to the same dimensions as the original 8 1/4 and either using the durango drum brakes or the original drums off the back of my 73 dart sport.

Also, any recommendation on a shop in houston that can do the work correctly?