This woudl be an interesting mesh of styles. Slatterys mobility and unorthodox boxing style vs LaMottas pressure. You might be inclined to give Slattery the edge north of 160, given the people he beat at light heavy. However LaMotta was much more consistent, and there isn't much between them physically.
Its been a while since I watched LaMotta, but I remember him boxing well against someone I can´t remember... I don´t like much of what I see of Slattery in the Berlenbach fight, but I know that is a limited footage that explains nothing...
Slattery is an ultra powderpuff version of Ali, if they can be compared at all, which I really think is nigh on to ridiculous. He has no chance against LaMotta. Berlenbach caught up with Jimmy in the 11th round, and Paul is by no stretch of the imagination even close to LaMotta.