I wouldn't hazard a guess at the value because of it's "uniqueness". I think a lot of folks will give it one look, make the assumption "that's not right" and move on. Secondly, there's no "market data" for any such beast like it.
The other thought this marriage has inspired is that the 414 frame was probably never designed to have a 35lb static load hanging off it's backside, i would provide internal bracing/support to bear much of the weight load in any installation.

