Ever since I've owned the IROC, I've had a grinding noise from the front when I'm on full right lock.
Now of course, the simple thing to do is not put her on full RH lock!
Of course, that's not actually solving the issue. Something's not right.
5 months ago, I had new rod ends fitted and the alignment sorted, and that hasn't cured it.

Just wondering if anyone has any suggestions as to where I should start looking next?

You shouldn't get near lock should you? Isn't that really bad for the steering box with the pressure?

is this metal on metal rubbing, or the tires rubbing? are there any marks in the wheel well s from where the tires are rubbing is that is the case? do the have the proper wheel on teh front (assuming you have 16" iroc wheels)? they are marked front and rear and the rears dont work on the front with stock brakes.

As a rule, I try to never put any car on full lock - if I can help it.
There are always going to be moments where it's unavoidable - we've got some narrow parking spaces and streets in the UK!

It's not the tyres rubbing, it sounds much more like a metal on metal sort of noise. Yeah, the front/rear wheels are in the right places, she's running the 16's.
I did wonder about the tyres rubbing on something, but as I couldn't source any 245/55/16 tyres anywhere in the UK, I've had to drop her onto 245/45/16's on the front, and I wondered if that was going to help. It hasn't.
When we changed the tyres, I had a good poke around the wheel well and there really wasn't any sign of scuffing or rubbing.

Could it be something like the lower ball joint?

Check K-member bolts and k-member brace bolts... Mine were loose causing a metal popping noise.. Could be something simple might not need new parts.