How well can you shoot out to 225 to 250 yards? That is about the furthest you could hope to shoot and still keep your shots less than 3" high or low all along that full range from muzzle to end target, unless you are loading some real snappy ammo.

Unfortunately for me distances beyond about 200 yards are history for me because of my eyesight and my abilities now.

With standard factory ammo and your 270 I'd try real hard to get to a 100 yard range and set it up to be about 1.75" high at 100 yrds. Then, if you do your part, shots out to 225 yrds should be do-able without a lot of in-field calculating or hold-over, etc. That should keep your shots within 3" high or low (or less) of your intended POI. If you fully intend to shoot out to the maximum 350 yards (you say your stand has access to) you'd better put in some range time at the actual distances.

Nothing will give you better results than ACTUALLY shooting at all the ranges you feel will be possible for you in the field.