need help with upgrading my 8 1/4 rear end.!

Thank you. I will know cam info next week when we start the rebuild and order parts.
Driving is just going to be cruising around enjoying the car. Driving to car shows and cruise ins. Of course having some fun smoking some tires and getting on it every now and then. But will not be at drag strip any that I am planing for awhile. As for converter do you have any suggestion with a mild 340 build to 400 hp. And a B&M or TCI auto 727 trans.