Manley Chinook Owners Tube Rolling

Yes, it will make a difference.
Knock yourself out
I'd start with the Telefunken ECC88.

Do you have tube linestage as well?  I ask because I tried tube rolling in my Herron VTPH2A with poor results - ended up going back to the ones Keith provided as they clearly sounded the best.  However I did roll the two 6922's in my linestage, replacing them with early 70s NOS 7308 Mullards sourced from Brent Jessee and it made huge upside difference.

You just bought it.

Listen to your records and enjoy them for at least a month. Asking about changing an already good setup, is a not a good sign.
I tried both versions of the Chinook. It's a great unit either way. Tube rolling is subjective, it can be very subtle,or not noticeable at all depending on your own ears/system.