Staszek,
That picture was taken 2 years ago!
Yes, all the details of the place are correct! I have tears in my eyes when I recal lthat drive, really first one: FIP was reveresed 180 degrees, switches on gearbox not working, vacuum leaking from the brakes booster, stuck steering knuckle, noisy differential, blinker working sometimes only, rattling everywhere, fuel leaking, ignition out of tune, idle out of tune - that was fun! Two pages of remarks and items to fix - over winter...
No, no chamapagne - I was born and raised on vodka...
Last Saturday, the first probably so warm and nice this year, I was also parking on the same spot
. Used Pagoda as every day driving car all day Saturday and Friday.
Lex, I am not a mechanic, so my advise may not be of value really...
But look at this:
https://www.sl113.org/wiki/Electrical/TransistorIgnition I think it talks '69 280SL. I think you have the components you mentioned described there, so it might be that your dwell is ok (but this is only what SEEMS correct to me - I cannot provide responsible advise with my knowledge level). This dwell, I think, needs to work with specific coil that can load in shorter time if I understand correctly. My dwell was different as I do not have the above mentioned elements (it was 38 degrees).
The system with the box under the battery helps during the start (resistor bypass for better spark), but I am not sure if its malfunction affects only the cold start. You would need educated voice here. You have the test procedure there.
For cold start there is also a number of aids in your car to look at... I have recently spotted the issue with my Thermo Time Switch that was not providing voltage to CSV when cold. But it is another thread, I guess and you say your CSV works.
Pawel