Undoing shift "improvements"

My 42RH transmission has just been rebuilt and still has a hard 1-2 shift that I would like to soften up for street use. I think it may have been modified at some point as the accumulator springs were missing. The larger accumulator spring was replaced from a donor TF transmission but not the smaller one under the piston as it seems many transmissions don't use these.

I think the shop that is doing the work is pretty good but most of their work is on European transmissions so they might have missed any subtle modifications.
Is there anything we should be checking for - drilled out parts of the valve body, missing check ball, non standard springs etc that would firm up the 1-2 shift if modifying for performance?