Cool, I'll have a look at the head for a date.
Usually takes the form of a round 'dartboard' 12-segment marking with two-digit year, e.g. "88" in the centre, and dots around the outside marking the month of construction (thanks for jogging my memory, Louie!)
Re-torquing might be an obsolete thing anyway. It used to be that head gaskets were supposed to be re-torqued after a few hundred miles. Federal-Mogul sells their Fel Pro PermaTorque brand that specifically doesn't need to be re-torqued. Maybe head gaskets haven't needed to be re-torqued for decades anyway...
Yes, I think you're right - about three decades, in fact!
The main change on FIAT engines happened around 1980 with the use of 'stretch' (torque-to-yield) bolts of a smaller 10mm diameter (in place of the 12mm studs and nuts). These bolts are angle-tightened (as Louie said) - tightened to a low torque figure (I think 20 then 40Nm), and then tightened through 90 degrees, then a further 90 degrees. This angle-tightening is intended to exert a pre-determined tension that makes it unnecessary to retorque at a later date.
All Uno engines used this angle-tightening system (along with most other manufacturers).
I was never fond of the idea of re-torquing, as parts usually had to be removed to reach the head bolts/nuts, and that was likely to cause leaks.
I believe that new bolts are a good idea, since the bolts stretch during installation. FIAT said they could be re-used a few times, but my experience was that the second 90 degrees is very, very difficult with old bolts, and I had a head gasket failure between cylinders - no problems after I reassembled with new bolts.
As for Mal Simmonds - away on holiday - with Christmas/New Year in the summertime, lots of New Zealanders take a couple of weeks' holiday at this time of the year. He's usually very reponsive, the rest of the year. There are other suppliers of course, but I know that Mal has sent to the USA before.
-Alex