I seem to have gotten rid of (I am hesitant to say "solved" as I am not quite sure what the exact problem was) the cold start issue. Car has now started (almost instantly with no cranking at all!) half a dozen times at -20C and colder.

What I did to car...

1) put lots of methyl hydrate in gas tank
2) replaced fuel filter (although old one seemed fine - could blow through it)
3) tightened intake manifold bolts 1/2 to 3/4 turns each (i had removed manifold and installed new gasket but never retorqued nuts after running engine)
4) end cap on elbow joint of vacuum hose connection at brake servo broke offbn as i was driving into the driveway as result I almost put car through garage door as no power brakes. Diagnosed this and repaired by hot gluing beer cap over top of elbow - works excellent! I suspect that this was leaking vacuum before and had probably contributed to vacuum leak related cold start issues.
5) cleaned intake bellows and applied silicone to the small cracks in it.

Thanks for pointing me in direction of vacuum leaks
Angus
--
1985 740 GLE, 1981 245 Ice racers