Check your ignition timing before you do anything else.
Then, check float height, then accelerator pump jets, for a blockage. Even if one is blocked you'll get the symptoms.
With a standard engine, and 55 F8's you should have no bog on progression, (unless they've been drilled incorrectly (not so uncommon !) 60 F8's are way too big for a 2 liitre, and will mask another problem.
You may need 55 F8's with RJ's cams.
I have 151's on my engine (warm 2 litre), and run 50 F8's with no bog, with 55 F8's i use more fuel can't get the right coloured plug.
Presume you're running the standard mech pump if it's taking a long time to start ?
I have a Mitsuba electric pump fitted.
I turn the key, let the pump fill the carbs, in cold weather, three dabs on the throttle, and it starts instantly. No long cranking periods, no throttle pumping.
The jetting spec I am running is :-
F16 Em Tubes
50 F8 Idles
35 Accelerator Pumps
Hope that helps
1963 Giulia Ti Super Rep, 1975 Alfa S2 Spider 2000 Veloce in Giallo Pagoda