Any chassis with the LOP you need. They vary quite a bit even with adjustable stocks. TAC21 is 1.5" or so less LOP than the LSS, both from the same MFG. That and a chassis that does not contain the scope base/rail but rather the rail bolts directly to the action. If you need to remove the action from the chassis when the optics are mounted to the chassis, it is likely you will need to re-zero.