200-4R Behind a 340 and Reid Bellhousing Build

The tunnel does have to be significantly modified for the 42RH though, right? I know the cross member has to be modified with both, but seems like the 2004-r would be easier? (just my sense)

Not so much as a dent in the tunnel, just the cross over top channel and under with the fabbed bracket.
I have about 450 into mine and that's transmission, shift kit and all.