Pin-Tailed Whydahs and St.Helena Waxbills

[Jbird]

Hello I am new to breeding Pin-Tails and was wondering if someone could answer a few questions for me.
I am building a small flight cage to breed this species.
I have 2 size options I would like to know which would be the better option and how many Whydah's and how many pairs of St.Helena Waxbills would be ideal to fit in them.

Size 1- 50"Wx24"Lx36"H
Size 2- 36"Wx36"Lx50"H

Any input would be great.
Also another question I need answered is when breeding the Pin-Tails do I have to use the St.Helenas as the hosts or can I substitute them for Red Eared Waxbills?

[Finchgirl]

The bigger the cage, the better! Always give your birds as much room as possible. Flight cages should always be wider than they are tall. You can use the cage calculator in the finch information center( link on the left side of the screen) to find out how many birds you can house in that cage. I would say no more than eight birds. From my reading I have gathered that only St. Helenas will take control of the nest, but I am no whyda expert.