James -
It kind of boils down to a bag issue more so then a rest issue, in most scenario's.
As to say, you could buy about any rest (or top), but what matters is the bag and it's thickness and width, and if it is thick enough to keep the 1/2" minimal required height above all containment. Example:
- my Sinclair rest and top is legal with my current Protektor bag. But if I replaced the bag with a thinner one, it would not comply with the rules.
No rests and bag are deemed legal by purchase only.....
They all have to confirm to be legal (just as my Sinclair example) with your rifle in place.
There is also stock designs that may infringe the rules in certain rests as well.
There are also add-ons that could infringe the rules, if bolted on.
I also suggest you contact one of the LR committee members and discuss these matters and your questions first hand with them.
Instead of having to read threw scrutinized replies trying to grasp answers to your questions (like happened to you on AccuShooter. com)
Here is a Link to the IBS LR committee:
http://internationalbenchrest.com/about/officers.php
Donovan