Do the above then get it to operating temperature and drain everything liquid from it. Start with engine
oil and coolant. Then drive it t lo get it good and warm and change clutch and brake and differential fluids and oils. Anything that runs get rid of it and start over. I'd also advise changing all belts and hoses in the process.
And don't forget tires. They probably have flat spots and are likely checked. They might be ok for casual street use but any spirited driving especially on the track would not be advised.
Don't forget a new battery.
Edit: is this a car or just the engine? If engine I would still do the first half of changing everything that flows