the guy could have sold you one thing and given you the manual from another... does the hatch have a portion of the vertical fin on the back of it? only about 3/4"

if the rear former is broken, you might try calling BV and see what a new former would cost. your other option is to create a gusset to cover the break I would go at least 2" either side of the break. the gusset should follow the same shape as the original former, basically laminating a piece to it. i would make it the same thickness as the original former.

i would not go crazy trying to reinforce too much on this. it will add weight very quickly.

I would compare the formers the gear is installed on against the documentation. My guess is that the formers have been modified to a point the bvm gear won't work. the price tag for the bv gear might scare you off a bit as well.

this thing is so tricked up from the original, i don't think too many folks here can help without actually seeing and digging into the model. i would not trust this particular airframe to a turbine. i would not spend any money in that direction. to the guys who have responded that know the BV F-16 intimately, not just the wings are different. bolt in whatever fan the guy modified this thing to accomodate, and see if it flies. and learn whatever you can take from this experience.