Goodmornings never really play "an essential part" any more than any other assistance.
Do the speed work first. And just do 6 to 8 X 2. If they at this point reduce you ability to do the heavy deads then reduce them. But at this stage of speed work you should get an immediate response for them and actually potentiate the heavy deads, just like happend when we did that is TM. But in that case why didn't you put them first?
I thought about suggesting putting in some speed work. I don't think you "need" it necessarily but that doens't mean it won't help. But you know my philosophy. See what happens before you add anything. Just because you take out goodmornings, which were only their becasue you wanted them
does not automatically mean you need to put in another big compound. If your continue to progress at a comparable rate then all is well.
It is most people impulse to add exercises with the more is better attitude. However, speed work should be fine for now.