I'm in the process of moving a shower drain in a concrete basement floor to line up with a new shower enclosure (old was rectangular, new will be corner).

I've uncovered the p-trap and discovered that it was cast iron, but upon some more concrete smashing, that they used what look like the Fernco connectors I see in the stores today.

I'm wondering if it's advisable to just disconnect the current p-trap, and connect up the new PVC extension/trap to get it to line up with the new shower drain location? Or will I need to dig back a bit further to replace the connector with something that will fit the OD of the PVC?

Here's some pictures, hopefully they explain better than the words above. The first is where I'd like the new drain location to be. My plan would be to put a single elbow (I'm hoping 45deg will be all that's needed) and move the trap to the left as shown.

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Here's a picture of the existing cast iron trap with connector. Note the PVC end is 1.5" and appears to just be friction fit into the cast iron trap.

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Thanks in advance for any/all help!