using fillet on a complex solid

[jongor 10]

So, using the help and methods from you guys here I've muddled my way through and created a nice smooth radius edge on this next body.

 

I did it by using Loft between arcs that I measured along the outline, which created a surface.

 

How can make the surface, and the hollow area under it a solid so it can be Unioned to the rest of the body?

 

Please see attached.

 

thanks!

 

3d Std J body-new.zip