2004 LQ9 X-Star Service discrepancies

[So.Cal_X-Star]

Newbie post but wanted to get some valid information before I dig into servicing this boat.

History - Just purchased a 04 X-Star LQ9 with 280hrs. Boat has sat for approx one year until I demoed it. I am performing the following service for the 300hr mark and to get it up to par with my OCD mechanic standards.

Change engine and v drive oil, replace spark plugs and possible wires, Replace Serp belt, and flush closed cooling system with recommended coolant. Already replaced impeller, the steering cable, and converted to new style rudder which made a major difference.

There is conflicting information on what the oil capacity is for the LQ9 one manual says 7.5 with filter other says 5.5 with filter. Same with v drive oil ? Also what is the proper plugs and gap I purchased NGK TR-55 and gapped at .50 but wanted to make sure these are correct before instailling.

Any other insight and recommendations for 300hr service would be greatly appreciated. Thank you in advance. Look forward to hitting the water in a MC after years of headache in my Tige.