904 and 8 3/4" gasket advice

The man I bought it from said the transmission has been rebuilt before while he owned it, my guess is they rebuilt it when they put the 360 in. Now, when I bought the car in 2015 the registration tags were for August of 2002. I'm really hoping it's just a dry rotted input shaft seal, but we will see when it comes out next week (or the week after). I'll be sure to keep everyone updated!