Pipe from wall is too long for tub spout
I have a tub with a spout that uses a bottom-up diverter. It is old, corroded and does not work properly. I bought a replacement delta top-down diverter spout. The problem is the pipe from the wall is too long and if I screw the new spout on I am left with 1-1.5” of exposed pipe. I am unsure how to proceed. Do I cut the pipe? The new spout has an adaptor for a non-threaded pipe but I am not sure I trust that. Or can I buy a shorter or adjustable adaptor (the long piece of plastic inside the spout that attaches to the wall pipe)? Thanks.