Same with mine
When I purchased my 67 350 the original engine and 4 speed was removed
Wrapped in plastic and sits in a safe spot in the garage
Then had a nasty little 331 built from a 67 block
With a Holley sniper, 5 speed etc
Looks completely stock and no risk of damage to the original engine
Win win, with lots of Smokey tires
My original engine out of 6s843 sleeps in a closet wrapped up in a blanket on the main floor of my house. Current engine is a roller rocker late 80s 302 that came out of a drag car. If it blows up, I don't care. Original tucked away and safe.