Ronald, you'll need a case. The best TH400 cases are the HD ones. Right now, there's two on ebay.
I suggest you find a transmission shop in your area that does performance work, and not a chain shop like Aamco, etc. Find a one owner shop.
When they deal with a customer in person, not via mail order, they'll do a better job. And you can go back if there's a problem.
Tell them you want all new frictions and steels, bands, seals, 34 element sprag and bearings. There may be some reliability and performance upgrades you'd be interested in such as a shift kit and roller bearings.
Give them you dipstick and tube so they can confirm the full mark is accurate.