MSD recdommends the 8251, 8252, and the 8261. The 8207 looks to be for the 6 series box and may not function properly with a 7 digital. The 8252 comes up as for the 6-box as well, so I couldn't tell you for sure. You might try checking with their tech dept. online or by phone. They have always been very helpful for me.

FYI - the 7531 box is NOT allowed for NHRA competition. The "slew rate" function could be used as traction control which is banned.