I think you're a bit confused about the terms... "longblock" vs. "shortblock" is just a quick way of indicating how much of the engine is included in the sale.
"longblock" generally means you're getting the block and head together. You'll usually (but not always) get the valve cover and the oil pan. Sometimes you'll get the timing belt components and intake / exhaust manifolds, etc.
"shortblock" is just the block with no head (and hence no cams, no valve cover no manifolds no timing belt stuff, etc)
Somes times you'll see sales for a "bare block" (no pistons, rods, bearings, etc) or a "bare head" (no valvetrain).
The terms are a little squishy so definitely ask the seller exactly what's included.
Either way I'd definitely recommend you try to fix what you have first before going down the engine build road.