As many have replied, stock is best. I recall talking to a well informed Brit car guy and they tended to only do mods that were reversible with wrenches. The originals were kept. Modern stuff was used for the sunny day tea runs but a bit of wrenching made them competitive for the concours stuff.
One would have to ask a concours judge how de-modding was seen (Cut and weld followed by more cut and weld) and if it could be unnoticeable.
There are sites where you can shop for a motor by serial number, getting the right year.
Be careful where you store stuff. A guy I met had a Corvette with a very tired original engine and did an economy swap using a generic SB Chev junkyard engine. He stored the original at his brother's place and his SIL got in a clean the place mood. It got scrapped.
One would have to ask a concours judge how de-modding was seen (Cut and weld followed by more cut and weld) and if it could be unnoticeable.
There are sites where you can shop for a motor by serial number, getting the right year.
Be careful where you store stuff. A guy I met had a Corvette with a very tired original engine and did an economy swap using a generic SB Chev junkyard engine. He stored the original at his brother's place and his SIL got in a clean the place mood. It got scrapped.