Furnco donut into extra heavy CI

I want to pull out a piece of 2" Galvanized which is leaded into extra heavy cast iron and replace with PVC with furnco donut

A plumber told me that the furnco donut will be very difficult to squeeze into extra heany CI.

Anybody ever try this?

I find the donuts difficult to work with under any circumstances. I am not sure what extra heavy cast iron is. It is all heavey to me. If the galvanized is in good shape, can you leave a foot or so of it jointed to the cast iron and use a fernco coupling to transition to pvc?

From what I read, they make different doughnuts for the different versions of that fitting. If you have the heavy version it won't fit the regular stuff and vice-versa.