Any gains adding 1.6 rockers to stock 273?

Everyone keeps mentioning simple things. The Car already has an aftermarket electronic distributor. I have not had the chance to check timing curve rpm. Exhaust is stock manifolds, but aftermarket dual exhaust and Flowmaster mufflers (which I hate due to too much interior noise).

Thank you for that tidbit!!! I was unaware of the need to modify the pushrod holes!

As far as pushrods, I can change the adjusters out to ball style quite easily.
You are defeating the advantage of the 1:6 by changing back to ball adjusters. Plus I think you will still need custom pushrods.