Hi all, I am installing a new upstairs bathroom and need to tie in new plastic 110mm soil pipe stack to old cast-iron 100mm vent pipe. I purchased a SP140b connector thinking it was a simple job but sadly the internal diameter of the metal pipe is a few mm too small to get the connector in . I have found a Flex seal option (tightening up with jubilee clips) but not over keen on this as it's above ground (supplier does say they are suitable for above ground) . Any other options/ideas? I am trying to avoid digging up concrete and trying to connect to clay below ground if possible as this will be a much bigger job . Thanks in advance