Sell it or keep it?

This may be more fitting for the Classic Talk forum...but here goes anyway. When I purchased my 67 mustang, it was all original, except for the paint. The guy selling me the car didnt know that, but after identifying all of the casting numbers, tags, stamps, etc...I came to the conclusion that the car still had its original drivetrain. My car is a regular v8 auto ps/ac console coupe, no GT or nothing like that. I am replacing the original C4 with a T5 and several other parts like that (eventually the original 289). So when I replace these parts, is it worth it to keep them? Stash them somewhere to keep them with the car? Or just sell them, make a little cash and have no clutter around my home? What would you do, given the non-rarity of the car?

I think if it's anything Identifiable to the car (engine, trans, rear) then I will keep it....old seats, gauges, body panels, exhaust manifolds, etc...I will sell to the first person needing them, or give if they ask nice enough. That's what I have been doing anyway.