Can someone please help with estimating the value of my E53 w/ blown engine?

[NOLA_X5]

2001 3.0i w/ 177K mi. The engine needs replacement due to blown head gasket. New axles and brakes, wheels and tires in bad shape (putting the orig set back on, which were under my house for last 10 yrs), dents in hood and front passenger fender from large tree branch, interior in excellent shape, but exterior shows signs of age/sun fading.

Someone is interested in buying it to replace engine, asking $1000, or should I sell it as salvage to a parts yard?

Thanks!!