While the Wilcap engine plate does work, it is is an ugly solution that even when properly trimmed can get in the way of virtually anything passing near the bellhousing. It also moves the transmission farther back in the car slightly by the thickness of the plate.
Using a Reid bellhousing does require cutting the bellhousing off the 2004R and bolting an adapter ring to the front pump housing of the 2004R.
I think I understand what you're saying after looking at some pictures. It looks like the Reid bellhousing is a much better solution. The transmission company building the tranny can do that work pretty easily while they're doing everythiung else.