I keep a collection of different rocker arms on hand so I can quickly check the geometry on new combinations. Crane rocker arms are the shortest and HS are the longest. If you bought one pair of Crane rocker arms that you give you a good comparison to what you have on there now.

T&D should fit correct on the SR heads but they are expensive. It isn't that easy to buy just a pair for checking becuase they use a smaller shaft size.

In the picture I posted the plain aluminum rocker arm is from Hughes. The Hughes rocker arm is mid-length. It is shorter than HS and longer than Crane. You might buy a couple of them just to check the geometry on your heads.