999 trans problem

I have a 89 999 trans in my 49 dodge truck. I just cahnged the fluid and the level looks good. When it shifts form 1 to 2 the rpms sometmes go up between the shift to 2. is this a band adjustment that is needed? maybe a shift kit will solve the problem? I would like to delay a rebuild until the winter if possable.

The 1-2 shift applies the kickdown band. It probably needs adjustment.