Over 44 years of driving TR6's the Michelin XAS's are the right tyre for this car, they really are blinking good for a narrow tyre like a 165. I changed my XAS's fairly recently as they were 9 years old. I drive my TR6 the way its meant to be driven so considered the XAS's again but oh the price had me reeling a bit. I plumped for 165 CN36's which were cheaper but only slightly. Both are a very good bet for a TR6 just be prepared to pay. They will last you a long time though and you can drive with confidence.
Good luck
Alan G