a basic rebuild kit will suffice for a sub400hp engine. youll also want to purchase thrust washers and thrust bearings, which can be found on EBay. i believe i bought mine from oregonperformancetransmission (or something like that). you can buy the rebuild kit locally for a little more $$ but at least youll have it in your possession right then, rather than waiting on shipping.
without any previous knowledge or experience, i tore down and rebuilt my 350 and installed a NoYoYo trans kit. the trans works perfectly and shifts great.
consider replacing some other parts, like the accumulator spring and case vent. check out www.bulkpart.com