Toilets, Sinks, Showers, Tubs and Disposals - ABS to Copper

I had to remove a metal (brass?) toilet flange that was attched to a 3 inch copper pipe with lead (at least, I think it was lead). I want to replace the metal flange with one of ABS. Since I will be putting ceramic tile on the floor it will be impossible to put a metal flange back anyway...not enough of the 3 inch pipe extruding. Is there a way to use an ABS to copper adapter...and, if so how do I seal the two ...the ABS and copper together. I've searched the forum but haven't seen this question asked... please forgive the redundancy if it has. A prompt reply (like, yesterday) would be very much appreciated. :-)

You can purchase a PVC toilet flange that fits inside of your 3 inch pipe - and seals with a rubber ring between the old pipe and the new flange. Be sure to securely fasten it to the floor to prevent movement.