T300 sleeper options - Looking for info

Good afternoon Everyone,

I'm looking for info on putting a factory Kenworth sleeper onto a 2005 Kenworth T300 straight truck.(class 6 box truck).

An example of what I'd like to retrofit is the 38" sleepers found on the 2010/2011 T800s. They seem roomy (enough), relatively lightweight and have walk-thru access (vs. crawl-thru with the earlier coffin sleepers).

Does anyone know if the T800 cab is materially or significantly different from the T300 such that nominal modifications would allow this type of sleeper installation?

One of the differences might be the roof line on the later model T800. It appears to have a greater rake than the 2005 T300. If this is true, would it be viable to swap roof skin? I've seen it done on a sleeper-to-day cab conversion but not the other way 'round.

Would like to use an "off-the-shelf" option versus custom due to budgetary constraints.

Thank you all in advance for your input and help!