Mighty big worms in that there can!
Bit like "Grandma's Broom"
A good example to debate, is Herr Hoebig's "Tiger".
Herr Hoebig was an owner of the famous "M. Murat's Field" in Trun. The tank is believed to be welded together from numerous bits. So, probably more bits with "Made in Germany" on them, than not. Looks like a Tiger, but somewhat more of a replica than a restoration, IMHO. The great G-13 v Hetzer debate is another example. The owners of "Hetzers" get very upset if someone suggests it's been assembled in Switzerland, taken to bits & reassembled with bits that weren't on it when it trundled through the alpine meadows!:cool2:
For me, I ain't fussed if your M36 Jackson has an engine from a T54 & evidence of a "roof" once being on it. Thanks for taking the time & paying a lot to get it trundling along.
If I was buying something and really wanted it to be a "proper" whatever, I'd probably expect the main structural bits to have come out of the appropriate factory, at the appropriate time, be armed with the correct weapon(s), have the right motor and gearbox and probably it's wheels being period pieces too.