kyle,
I have actually an adult female Brazilian Rainbow gravid, Shes about to give birth at anytime now...
She was 5 years old when she was breed for the first time...
I must say that, It doesnt look that she is gravid sometimes, it is also difficult to feel them..
It is her first litter, so she may be not having LOT of babies,
But I can tell that the babies are not necessarely bigger, Because mine is about a little more than 6 feet long and she dont really look gravid and for smaller ones, it shows ALOT... So it looks like they will be the same size as others would be...
But anyway I'll see when they will get out....
But Bigger they are, bigger are the chances that they get 20-30 babies or even more.
So in conclusions, my thoughts are that the babies themslef wont be bigger, but they will be more of them..
Maybe if she has babies early, it could affect her growth (Anyone correct me if Im wrong !!!) . Dont forget that she wont eat for MONTHS ! and you have to be sure that she will have a correct weight before the breeding attempts.
I hope this will help...
Good luck