rear housing

I want to narrow a rear end housing for my 66 dart which im going to be using a 489 center section. What will be the least expensive housing I can find? Its the one thing I wish I had done in the first place instead of using an A body rear. Believe it or not it keeps me up at night thinking I should have done that in the first place. Maybe i should narrow the A body housing since I already cut and moved the spring perches in?
What are your thoughts?
Thanks Rod
Cheapest option is to use what you have. 2nd cheapest option would be to source a C body or truck 8.75 and cut it down.