I suppose here are my suggestions from what is available currently
early cars are easy 185/70VR15 and 215/70VR15 are both available from Avon CR6ZZ https://www.longstonetyres.co....yres/avon-cr6zz.html or Michelin XWX https://www.longstonetyres.co....es/michelin-xwx.html I would fit XWX. they are more of a road tyre. Pirelli make both these sizes, but not in the same tread pattern. and XWX is of course correct. XWX came out at the end of the '60s and was their flag ship tyre which was being fitted to cars like 6.9 Mercedes Ferrari's, and the early Countach.
this gets tricky. Goodyear aren't making any classic tyres. (except a few crossply tyres for pre war Model A Ford). we would really like to go down the rout of Pirelli's CN12, https://www.longstonetyres.co....-cinturato/cn12.html because it is period (1971). It has a very high speed rating (W), they are the only company to make the correct 255/60VR15. It wouldn't suprise meif they were a European option, becvause not many commpanies made thsi size tyre, but Pirelli did for the Aston Martin Vantage and the Lamborghini Muira SV. However Pirelli don't make a 205/60VR15 (why would you. it is not a comon classic car size) Pirelli do make a 205/70WR15 Cinturato CN12 which is high performance and matches the 255/60WR15 CN12 Rear. I suppose the question is can you fit a 205/70WR15 in the front. They will be a b it taller. Pirelli do also make a 215/60R15 CN36 wich will bit a little larger, but have a different tread pattern. However all these CN12 and CN36 tread patterns will be great road tyres and handle really well. The next best option i would think will again be Avon CR6 ZZ they do make a 275/55 https://www.longstonetyres.co....vr15-avon-cr6zz.html then you are left with the choice of 205/70VR15 or 215/60R15 again. If 205/70VR15 fits then you will be better off on the road with Pirelli, but if you need to fit 215/60R15 or 185/70VR15 then you do have the option of having the same tread pattern. Although i am a fan of same smaaller tyres on cars i think if you up the size of the rear, reverting back to 185/70 on the front could lead to some dramatic under steer, with the power on. I still think if you can fit 205/70 on the fron CN12 is the best option.
225/50R15 is easy https://www.longstonetyres.co....relli-cinturato.html they are on the shelf. what you do for the 285/50R15 rears for now i don't know, with there being only 100 cars it is difficult to ask a tyre manufacturer to make them
285/40R15 easy they are on the way from Pirelli. 345/35R15 No problem. i should have them in a month or so https://www.longstonetyres.co....li-cinturato-p7.html