The common engines for a 2005 Chrysler 300 were:
* 2.7L V6: This is the smaller engine option. Replacing it would likely require a similar V6 engine of comparable size and configuration. Finding a direct replacement would be easiest.
* 3.5L V6: This was a more common engine. Again, a similar displacement V6 would be the most likely candidate for a replacement.
* 5.7L Hemi V8: This is the powerful performance option. Replacing this would also ideally require another Hemi V8 of a similar displacement, though there might be some limited options for slightly different Hemi engines (with significant adaptation work).
In short: You need to specify *which engine is currently in your 2005 Chrysler 300* to get a relevant answer. Then you can look for a used engine of the same type or possibly a slightly modified version from a similar-year Chrysler model.
Replacing an engine is a major undertaking, best left to experienced mechanics. Improper installation can lead to serious problems.
