I wouldn't worry about breaking an 8 inch rear until you had 300 hp to the tires, super traction, and were doing severe clutch drops or using a trans brake. Most 8s have the same axles as the light 9s. 8s are getting very popular in the street rod crowd because they are very stout, cheap, and easily available in the popular width, e.g. 70s Granada. $100 wheel to wheel, or $50 or less for the center chunk, unless it is a 70s Traction-Lock which brings $300.. avoid the Equa-Lock if possible..... no parts available.
Grab a 3.50 gear from a mid 66-67 Fairlane OD car, or a 3.55 from a V6 Mustang II. Hope for a Traction Lock differential.