I've actually done a few with the gt350 tb w/o issue. I have some stock gt350 tunes that could help.
Going against the grain here but that manifold doesn't actually gain nearly as much as people say. It actually sacrifices power all the way to about 6800. Most people are comparing a tuned gt350 manifold car to a stock tune 15. Here's a graph showing stock vs tuned vs gt350 on the same car. And yes I spent a ton of time on cam timing on both manifolds
gt350 vs stock manifold (1).jpg
Edit: Just realized that graph is standard corrected. Not that it really matters for the comparison but I don't typically use std #'s