Ok,

new ring gear and a new timing chain fitted, along with a full fluids change, oil filter, new clutch and replacement shocks.

She's never sounded as sweet and revs up beautifully, ticking over at 750 solid. No more rattles from the engine and no more smoke from the air intake.

One thing - I replaced the 20/50 that I was using with 15/40 diesel engine oil after reading on here that it was a better quality oil. Now my oil pressure takes a lot longer to come up to 6 on the gauge than before - is this normal/ok?

Thanks for the advice here, she's running like a champ now!