Welcome to TDP
Yes you can do a swap.
Use the 6.5 heads.
Change the injectors over to the proper POP pressure for the mechanical Injection pump....
The 6.5 heads have a different angle on the injector location....
You will likely need to scare up a set of 1992/93 6.5 injector lines to finish off the swap.
Now....the one caveat.........
If you have air conditioning installed (Factory type) the turbo will hit the AC box
Without AC and things can be fit in quite nicely.
You don't have to fool with the timing cover, water pump or any of that stuff.
Swap the heads (Use the Felpro gaskets and new head bolts)
Swap the 92/93 injector lines
Do your exhaust
Good to go
The original Banks turbo kits for the Square body trucks made very similar if not better power with the 6.2 than the factory 6.5 did.
The Banks turbo kits had better exhaust flow....
You might be better off scaring up a Banks kit and going that route...
No need to rip the engine down and or buy different fuel lines and such.
Just sayin
Have fun
Keep us in the loop....always great to see these venerable older rigs being massaged...