Just replaced a K70 on a Notrun this afternoon - it did just on 3K miles on a 650SS and was well dead. TT100 on both ends now, and we'll see.
Avon Roadriders are nice but look a bit funny to me on oldies. Had them on a café-racer and they were pretty good on the bendy bits, but out of place maybe on most classics in more standard trim.
SMs on a couple of all-year workhorses have done pretty well, and I also find they handle OK with my fat backside holding things down. On the A I was getting about 5-6K miles on rears - a TT100 on there now is half worn at about 1800 miles though.
A tyre I do like is the Pirelli Scorpion for rims that will take one - that's not 19" wheels I think. A similar-ish 19 inch Pirelli MT-something is OK too - but short life is guaranteed on the bike I have these things on (P11 desert sled). And the look of them isn't exactly period either. I think Ducati fit them on their Scramblers, or did, and they're pretty OK on the road (how many of those bikes ever go off it, for that matter?)
I'm going to stick with TT100s for the time being on the A, the Notrun and one AMC twin, having bought a car-bootload last time I passed Vintage Tyres in the UK. Pirellis for the P, and SMs on 2 others for economy reasons. Haven't tried Mitas - but a lot of friends like them, price-wise they're good and they seem to last pretty well. I rode a pre-unit Triumph with them on and it seemed fine - but it was a bike I'd done the engine on for someone else, not mine, so didn't explore the limits.
No risk of tyres cracking up or going out of date before wearing out round here, so I suppose that's something! But if there is one job I just don't like these days, it's tyre fitting . . . Is it the compounds, or what? Used to be able to get new ones on without levers almost every time - but not nowadays. Feeble with age? Or they're made of less forgiving stuff maybe.
While I'm on, since having a blow-out on the A a couple of years ago on a dual carriageway, I now only fit Michelin 4mm thick inner tubes, for scrambles I believe, to everything in the shed. And I always replace them with each tyre change, plus new rim tape. Bloody difficult sometimes to get them into front tyres - but no more problems with sudden deflation and/or valves ripping out on some of the tubes I've had in recent years (from god knows where probably). Could have killed me when the rear SM went on the A - glanced off central armco barrier and then off a concrete near-side barrier while getting the thing under semi-control with the tyre blown clean off the rim and the back hanging out 45° from straight. The extra cost of the heavy-duty tubes is worth it - and a hell of a lot less than the new rim, spokes, tyre etc etc that I had to sort after that incident.