What is the caliber of your TX 200? There will be more drop at thirty yards with a .22 than with a .177. What do you mean by low - an inch, a foot, a yard? Fixed non compensated rings should be fine on a fixed barrel rifle. You will need high rings so the objective clears the barrel. My TX 200 has zero droop and the point of impact at forty yards is only slightly lower than at twenty. It's a .177. I'm using a Hawke dovetail mount directly on the receiver.
Look at the physics of the set up ....If scope is optically centered your view threw it is parallel to the tube and mounts that will support it.The barrel and receiver are parallel making the scope dove tails mount attaches too all on the same plane.Whatever the scope height is ( Lets WAG @ 2 1/2" ) is the distance the pellets leaves muzzle LOWER than what scopes as viewed center line is.* So is you looked threw scope at a dot on a target a few feet in front of muzzle and shot a pellet the POI would / should be the same @ 2 1/2" difference.Now you have gravity pulling the pellet down and this value increases over distance.YES shooting low is going to happen !!Now if the UPWARD ELEVATION using turret correction is not able to compensate and raise POI at 30 yards ( Ideally being 1/4 or less of the total adjustment range turrets provide * If you have say 80 clicks either side of zero, then no more than 20+ to 20- ) then you need to go with adjustable mounts that in use are reverse of Droop actually creating a Muzzle higher than scope view condition. Loose numbers presented, but to give you some idea on whats happening.