1000hp 727 full manual build
If you talked with Chris Andrews, he will steer you in the right direction. No doubt it will handle that much power. Your wallet is going to be hurting.
I just did 3 727s that are all built for very high HP. Two are going in 3400lb roadrunners with over 900hp and one is going in my own race car that will be pushing 900HP.
I posted in the racer forum the parts list on the two 727s that are in 3400lb roadrunners. Stay away from aluminum drums though. Definitely billet steel over aluminum.
Thread 'Winter transmission builds'
https://www.forabodiesonly.com/mopar/threads/winter-transmission-builds.555868/