Noise at High RPM

[EdderSpisder]

Hi.
Need your advices and comments for a noise issue that i'm facing in a new fresh engine with only 350 miles.
It's a Spider 74 with a 1756cc. My machinist changed piston rings and high compresion pistons, oil and water pumps, valves, used auxiliary shaft (good conditions), crankshaft (good conditions) and rod bearing set.
As feedback. When my machinish finished all the work, He recommend me to run the car slowly for 300 miles (Not over 35 Mi/Hr)and i followed his instructions but during this weekend i decided to run in the highway with a speed of 50 Mi/Hr in a distante of 30 miles and what my surprise that i heard a noise over 3000 RPM when I was in 4th and 5th shifts. The noise comes from the cams (believe) due is a tak tak tak.
He said the noise is in the lifters because they need calibration but I'm not sure due i had an issue in the past with lifters and they sound in low and high RPMs.
Any recommendation? Thanks because i'm not going to sleep this night if the issue is high.

[azruss]

These cars do not have lifters, but shims between the cams and valves. These can be replaced with thicker or thinner one to adjust the gap. Your mechanic should have measured the gap and made the adjustment. If he didn't then it better get done sooner than later.

[EdderSpisder]

I used an octane increaser based in Machinist follow-up but still the noise.....
He said next step is to measure the preasure of the cilinders, then timing.....