Can someone point me in the right direction for a buffer system on a 7.5" SBR? My first build and I've seen so many mixed opinions on buffers and what does/doesn't work. Different weights, springs, etc. If anybody has experience with this and can give me a suggestion I'd greatly appreciate it!

There is no right answer for this. It's a trial and error process for those willing to experiment with it. A carbine length buffer spring will be fine so leave that alone. Begin with the regular carbine buffer and see how your BCG cycles. If you feel like it's cycling too hard, get a heavier buffer or an adjustable gas block. If you're comfortable with the way it cycles and it has no issues, then leave it alone.

a good place to start is a H or H2 or Spikes Tactical ST-T2

Right answer.  I start with a H buffer and standard carbine spring.  You won't know until you get it to the range and see what it likes.  Try different ammo also.

I have a H buffer in 1 pistol and a ST12 in the other.

Thanks all for the input. I'll start with H and see how it goes!