A couple of used pressure relief valves from two engines – yes, they are different sizes but compare the wear pattern to yours.
And are these ok? Low profile cam gear bolts https://www.coolairvw.co.uk/Item/Sh...1304L/Low_Profile_Camshaft_Gear_Bolt_Kit.html
They’re for a type 1, you need five bolts for a type 4 and you’ll probably still have to machine the heads thinner.
So i am interested to know the effect of a spring with a slightly less loaded pressure. Would it give a lower pressure when the oil is thick/cold due to more bypass. I suppose also less going through the cooler until the oil gets hot & thinner. Bit of a balancing act I suppose.