Thoughts on tuning older/longer bows?

[koger]

I recently bougt 3 older bows, and am having fits trying to get them tuned. They are as follows. Hoyt stick on rest.
Ben Pearson Palomino, 66" #30@28, absolutely stunning bow. New string.

Blackhawk Apollo, 66", #44@28. Osage and black Phenolic, rug rest and plate.

Indian Archery, #40@28, 58", deep pistol grip, locator grip, rug rest. Looks like black walnut, with lots of birdseye in the wood.
I have mostly been shooting 35/55 GT's, 2000 vapors,2018-xx75's,Easton Carbons, 8.4's, all w/4 inch feathers. I finally got the #44  Blackhawk to shoot a Axis that was footed, great flight. I am getting a lot of tail whip, nock high on target. They are grouping well, just awful flight and that messes with my mind something awful when I am so used to getting good flight out of the other 12 bows that I own and shoot regularly in the #40-50 range. Is there a knack to tuning these older, longer bows. All replies appreciated.

[Mo. Huntin]

What weight broadhead are you using?, bet it is a lot. I am going to watch this one you seem to know what you are doing if you got 12 others to shoot for you, I hope to learn something.

[Apex Predator]

You are gonna need a lighter spined shaft for those other two.

[James Wrenn]

I agree with Apex.Your arrows are too stiff for those old bows.I am sure they have fat overbuilt b-50 strings and will need weaker spines.

[hvyhitter]

1816s for the 30# ......1916s for the other two.....

[koger]

I am shooting 150 field tips up front, no extra weight and yeah, these ares spined too heavy. But it is funny that the Easton Axis shot like a dream, I guess the foots on them weakened the spine just enough. The strings are  all new B-50, but not too big, about 14 strand, usual stuff. I have a box full of about 200 assorted alum. arrows in my attic, gonna dig them out and play with some of the lighter ones. Any more info appreciated, thanks all.