Alright. Thanks for the answers!
Don't forget the Balls should be subject to changes too. We are dealing with Expansionist Fetishes/Kinks. If you were gonna add any kind of Cumflation and Pregnancy, the multiplier (or similar) would be affected by those two. The Capacity "Balls", which then could affect Virility (pregnancy chance and multiplier) and Cocksize, which would be Output, meaning how much you release and how many times you shoot.
Just a pointer out. Hopefully, you take these into thoughts and decide how you wanna deal with this.
Remember. This is YOUR Project. What you decide, is ultimately up to you. We are simply giving you ideas, inspiration and questions that only YOU can answer. Make what you want. Consider the possibilities and options, within reasonable limits. Don't get too greedy, ambitious and overconfident.
I wish you the best of luck! I'll keep an eye on your progress.
Peace and take care!