WTB plastic BB 727 mock up trans

Just a suggestion that helped me on a '59 Dodge with a 6.1 Hemi;

Before rebuilding the trans, the gear and clutch assemblies and shafts, as well as the front pump housing and valve body all had to come out. This gave me the opportunity to just use the housing/ case and tailshaft housing, bolted together to manipulate and play with.

You can lift the housings bolted together with one hand. That may save you some time and searching, especially if you have any experience with trans building. It is actually quite easy to disassemble and reassemble.