Ian,
That 165/80R15 size tends to be hard to find & IIRC the Tire Crack one is a passenger car touring version, which may not matter if it's just your spare never to be rotated into service.
If all else fails locally or with Tire Crack - Lucas Tire, Universal, Coker, etc. also carry the Vredestien Sport+ in 165/80HR15 tubeless, which is correct for the 2L & -6, and their Sport in 165/80SR15 tubeless for 1.7/1.8 for about $110 IIRC. Lucas is in Ohio & IIRC so is Universal, but CAN may have similar vintage/classic car tire dealers too.
A local tire shop may be able to order them for you also, if you get the info online for them to see. I think TOD914 did that for his last 2 2L he restored/refreshed.
A lot of the early 911/912 & 914 guys have been using them, as well as some 356 guys I know around here for upsize from their stock "skinnies" (145 & 155).
Cheers!
Tom
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