Hi there Rosco7002, I think your last statement is correct.
First thing I'd ask you is how are your broadheads oriented? I've had some goofy flight from my bows at times and fixed it by reclocking my broadheads. I now prefer to have them clocked about 1:30 - 7:30 as seen with the arrow on the string and the bow held vertically. That way, when I cant my bow to my natural angle, they are level.
No idea how much you've messed with tuning trad bows but it sounds to me like you're a little bit too weak. 5/16 off of center is quite a lot compared to most bows. That's getting into selfbow territory. Certainly not a performance issue though if you get set up right. Having a draw length less than 28 inches, even if you shoot longer arrows takes less spine too.
For a right handed shooter, it has been my experience that stiff arrows kick right and impact left. What happens is that the string tracks towards the center of the bow during travel but there's a part of the bow riser in the arrows way. If properly tuned, as it passes over the shelf, your arrow will flex enough to just clear the riser and when it leaves the string, the arrow is bent with both nock and point to the right but the nock end is recovering quickly and recovers before the nock passes the bow. A couple decreasing oscillations are normal but they should not be drastic.
When the arrow is too stiff, instead of bending around the bow cleanly, it rides against the side of the sight window. This puts enough pressure on the shaft to force the point end away from center to the left. As the arrow clears the riser, it appears that it is kicking right because the point was forced to the left.
When too weak, it bends so much that as the nock passes the riser, it ends up to the left of the point thus it appears to kick left.
How thick is your strike plate? You might try removing it completely for a few shots to see if things improve. If you don't want to do that, You can try a heavier head but 190 grains doesn't leave much room for that. I don't even know of any heads heavier than that off hand. You could always pull the heads on a couple arrows and trim the tapered part back to about 3/4" long which will leave a cavity inside the ferrel of the head. Melt some solder into the head to bump up the weight and reinstall on your shaft. To be precise, either weigh each piece before melting it in or measure the length of the solder strand.
Last option would be some weaker spined arrows. I've got the opposite problem you have in that I have a gorilla draw of almost 32" and I have to play with spine a lot. Rule of thumb is add or subtract 1 spine group for every inch over or under the standard 28" draw. I have to go up 4 spine groups for my draw and you would have to go down 2. This is before bow performance is factored in. I'm thinking if your bow is 68# @ 27", it should be about 65 or 66 at 26 and being a string follow design, with a shallow cut shelf, it will probably shoot similar to a very well made selfbow. I'd try 50-55# arrows if you wanted to shoot standard 125 grain heads but I'm guessing you are going with heavier heads for better hunting performance and will want to stick with the 190's. I think you're probably real close to okay but 55-60's should put you in the sweet spot.