Have over 5000kms trouble free. Have floated vales quite a few times and lifters got noisey. Shut off for few hrs and they pump backup.

Huh? You might have had 5000km trouble free but the motors not. Ive not had trouble like that since a old 100k 318 with a couple lobes wiped off. But yours is a fresh crate motor.

But as others said, its time to inspect the top end. Adjust and hope you don't have to replace the cam and lifters.

At least your running it hard.