For a cost of under $50 I would bin all the guides with no 2nd thought.
Also I'd measure the valve stems, if they are worn more than .001" smaller then the top part near the collets, I'd replace them all too.
Mini parts are CHEAP compared to modern cars.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

so just replace the lot then? guides and Valves

on another note! I have roughly measured the bore (with a ruler I do not have a vernier caliper yet) at approx 72mm how big does this make my engine

Thanks Andy

well measuring with a ruler is very hit and miss as there is only 0.5mm difference between a 0.040" and a 0.060" overbore. Assuming its 0.060" over (1275 + 0.060 = 1328....) it is a 1330cc.

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"In two years time your car will be like a lady's clothes, out of date, my car will still be in fashion when I am dead" - Sir Alec speaking to Pininfarina

thank you. I'm aware that it was a bit vague but at least i have an idea for now. cheers