A 518 rebuild

Trans wouldn’t shift into overdrive , pulled pan and it had a lot brass in it , so pulling trans for rebuild . I talked to trans guy at dodge dealership and he’s been building Chrysler trans for 25 years , he said get a kit and bring me trans , said get extra thrust washers . I asked about heavy duty kit and he didn’t seem to concerned about it . Any input here guys on where I can get a kit and what I need , 3800 lb truck 5.2 magnum cam headers intake etc pretty mild May put a 100-150 nos later . Looking at putting 2500-3000 stall . I called trans parts shop in city and they want 139.00 for basic kit , I want to do this right so any input would be greatly appreciated .