I wouldn't have even offered $800, as that's halfway to a really kickass guitar.
As others said, '80s have no "vintage" collector value (around early '70s at latest for that)...and the build quality isn't close to what was being put out in the early '90s. About the only thing desireable from that era IMHO is Tim Shaw pickups. Other than that, '80s era are the last Gibsons I would consider.
IMHO, this guitar, based on the info provided, isn't worth what you offered. Despite all the frankensteining, there's always that slight chance it plays like butter and sounds like a demon choir, so for me, the ONLY way I'd ever consider buying it at all would be if it just played and sounded incredible against all odds and reason, in which case it could even be worth getting it properly restored. Some guitars DO just have the magic, even some that have had headstock breaks, neck resets, refrets, refins, cracks, splits, etc. All of those things kill their resale value, but they don't ALWAYS mean they're lifeless toneless boat anchors.
When he hears what the pawn shop will give him for it he'll be giving you a call.