mmm, they didn't make a twin engined B-29 alike... C-54(? ..C-46 I mean) Curtis/Wright Commando transport ?
...looks like it has a cooling fan (either geared or fixed) behind the prop, hence why B29 thoughts of engine and Hamilton Hyrostatic(?) Hub.
At first I didn't think so, as a lot of the standard images of the Convair conversion show the cockpit with a more pronounced "bubble", but then I read this...
the nose configuration and canopy has been changed a few times while a number of development companies and organizations have made use of it,
Not the PD-808, but it is from a nation somewhere close by. Like your Convair, this is not how the nose normally looks. This is a one-off that failed to attract customers...