71 Duster with 360 block big cam

My father and i purchased a 360 with a 904 and have no build sheet and owner had no idea what was in it.. It supposedly had been rebuilt and it has a purple cam in it but have no idea what size or if the motor has been bored over etc.. It starts and sounds very radikal. But our main issue is an Ignition electrical problem and the tranny is spewing fluid out of dipstick.. i replaced o ring and it didn't stop then bought a lokar dipstick for tranny and it doesn't seem to sit flush when sliding it into tranny so i haven't tried to see if it will now leak again.. i just thought to ask questions before sealing tranny pan and filling it with fluid just to find it leaking again,.. I would really appreciate anyone who has had this problem before to lend out some advise or resolve.. My name is Randy