Ticking/rattling- clutch implicated, I'm perplexed

[zestyfesty]

Hi Guys, hoping those with some expertise can share thoughts -

Engine has 900km on it since a full rebuild, including new clutch kit. We changed to E85 and upgraded (stock frame) turbo. These items aside, it has been a replacement of existing parts (new forged rods/pistons, bolts, bearings etc).

Chassis has 150,000km, standard 5spd gearbox which has never been opened.

Previous rebuild with same mechanic we got 47,000km of road and 3000km of competition use. I treat my car with mechanical sympathy and never abuse it.

These 900km have only been used on metro roads, light use. Since rebuild there has been an 'idle dip' occurring between gearshifts which mechanic was aware of. This appears to have exacerbated over the past couple of months; standing still, disengagement of the clutch (pressing pedal) drops engine idle and can stall occasionally when engine warm. On the move, engine speed drops rapidly between shifts and will stall if shift is slow.
I've wracked my beginner's level mechanical brain over this for a week.

There is a clear rattling/ticking noise with engine running, that wasn't there after engine was first completed. I thought perhaps this was a clutch bearing (pilot or release? causing noise and maybe poor alignment placing load on input shaft) or maybe an input shaft bearing problem. But the ticking increases in frequency with engine speed, suggesting non-transmission, however as explained the transmission is implicated through depressing clutch.
Noise appears to be concentrated at the front of the engine, not bell housing area (although this is not conclusive)
A light press of the clutch will illicit a change in the nature of the noise, and full clutch depression will drop revs 2-300rpm when sitting in neutral idling.
Any thoughts much appreciated (that car is booked in for inspection in 2 weeks)
I'm reluctant to drive it as it doesn't feel right/healthy, and I'm really perplexed.
Clive? Anyone?

I've tried to add youtube links below, bit of a dork with tech, so hope it works.

[https://youtu.be/-vIhbJs-x2I]
[https://youtu.be/0srtMa6RqWg]

Thanks
Jim