Tranny Rebuild Help 904

So I've finally come to the last part of the rebuild. I've got a 318 and 904 and looking to rebuild the transmission to stock. 72 Dodge Dart Swinger. The 318 puts out around 300 hp so nothing major there. To put it simply I know almost nothing about transmissions. I've rebuilt engines and all that stuff but never a tranny. What is the most cost-effective kit out there? Am I capable of doing it? Or should I have someone else do it? (The tranny place quoted $1850) I know this is broad but i've done some searching on here and found a lot of different suggestions. Just looking to narrow it down. Thanks