You mean I can do my own oil change and maintain the warranty?…
The best route for engine replacement under warranty is dealer records. The dealer can tell the warranty center "we changed the oil and air filters at this many miles and on this date" and it is all cut and dry.
The farther you get away from that the harder it is to prove anything. Come in with a box of parts store receipts and the dealer has no clue when exactly the oil was changed or at what miles or if it was all just returned a half hour later.
Most independent shops will will keep records and the dealer will generally accept them. If you are going to have an independent shop change oil on something with a warranty confirm they keep records and are using the correct oil/filters OR better yet provide your own and make sure they note it on the ticket.
I always change my own oil. Heck I built my truck myself. Dealer is changing the oil in the Bronco until it is out of warranty tho.
And yet a Corvette that came with a 350 is worthless at auction with a pickup 350. You might be correct on the 250 CHEVY straight six..... but that was for a price point, not performance. On a budget a manufacturer will use whatever is in over supply in anything they want to move. In a heavy truck vs a sports car there is no myth, the engine internals are different even if the block castings start out the same.
Once you get past "numbers matching" thing there isn't really drastic differences between them mechanically. Cam, intake/carb and exhaust will change a lot on their own before you even think about playing with compression/heads.
Not like they are going to have super exotic stuff in a 1978 Corvette engine.
Basically just playing with intake/exhaust and cam/lifters got the Mustang 5.0 40hp over a F-150 5.0 (and 75hp over a Crown Vic 5.0 which unlike the truck also had a roller cam)... but the truck had a better intake that wouldn't fit under a car hood.