Swap or rebuild?

$1000 budget.
Motor you have runs good.... Leave it alone.

Spend your money on the rest of the car:
Front suspension rebuild.
Brakes and brake lines.
Rubber seals to keep wind and water out.
Rebuild the door hinges.
Do minor cosmetics where the car looks nice.
Check and fix everything in the wiring, make sure all gauges, lights etc works per factory.
This is the stuff that most 40 year old cars need.

Having little helpers are fun, I have a picture of my 5 year old grandaughter running the head bolts down on my 340