A Few Issues With My 518 Conversion??

Ok, I just finished up the the 727 to 518 conversion, on my 73 340 duster, and I just had a couple of issues. When driving, it feels like their is a vibration. I am running a TCI part# 141250 converter, with a B&M balanced flex plate, since my 340 has a cast crank. Also, I had the drive shaft cut, balanced, and new u joint put in correctly, at a drive shaft shop. So, I don't know what the problem could be. The other problem it has is that its leaking lots of fluid from the dipstick. I am using the dipstick off my 727. Is the dipstick for the 518 different or something? I checked the rubber seal, and it still looks fine, but I will try replacing it still, to see if that fixes it, that's if theirs no difference between the 727 and 518. And the last issue it has is
with the shifting. When I manually shift it, it works like a dream, but it doest like to shift into second or higher automatically, unless I let off the gas and then step on it again. Could it be that the kickdown cable is out of adjustment? If so, how would I adjust it? Besides these few issues, I am loving it. It's definitely a big difference from the 727. Thanks in advance for the help.