Looking for input for arrow to run out of my Old Mountain Mesa r/d longbow 36lb @ 29in with ff string. Im currently running a heavy setup but would like some input on something like Carbon Express Predators or the like for a lighter arrow to target shoot with that wont break the bank. Where would you start or recommend? Thank you!

Maybe 600 spine but 700 spine should better. If the bow is not cut to center then might try 800 spine. I'm sure you'll get a lot of recommendations.

Its right around 1/8 before center plus side plate right now.

Carbon Tech Cheetah shafts are very light and should work well. Even with lots of point weight you should still have a fairly light arrow. Their 650 spine shafts are only 5.3 grains per inch.