As the 2300 has the capacity to flow more air, I decided to use a pair of 45DCOE9s that I have owned since new in the 70's. This has allowed me a wider range of choices for the venturi size, the better to optimize the performance characteristics. I also used the OKP manifold, as it is less of a compromise than modifying the original manifold. If you just look down the bores of the original manifold, you will see all sorts of curves and obstructions that will be left behind after you de-siamese them. These will reduce your airflow below optimum at best, and at worst create different airflow behaviors between cylinders. The small difference in cost between modifying the original and getting a manifold intended for Webers is smaller, in my opinion, than the performance penalty that you will suffer.
Yes, I used two cams specified by Richard Jemmison. It was during this process that I learned about the difference between the large 102 tappets and the smaller FNM tappets. If you wish, you would have a wider range of cam options than I had. However, I am entirely happy with the cam profiles that I am using. You can find my dyno charts elsewhere, showing a marked improvement in the torque curve over the stock cams using 40DCOM carbs. There is slightly more torque at lower RPM and a bunch more torque all the way to redline. Truly a remarkable transformation. As part of the change, I went from 33mm venturis in the 40DCOM carbs to 35mm in the 45DCOE. At some point I may experiment with 36 or 37mm venturis, or even 38, and changing the cam timing slightly. I'm in no hurry on that project, as the performance is excellent as-is. Very drivable around town, but exciting when opened up.
Meanwhile, we are very near the end in fabricating a production of intake plenums that copy the appearance of the original, but which will attach directly to Weber carburetors fitted to the OKP manifold. This plenum will then connect to the original air cleaner assembly, leaving a very nearly original appearance. I expect that a small, reversible modification to the bottom of the air cleaner housing will need to be made to accommodate the increased airflow. Mark S has already made this change with happy results.
If you copy my configuration, then my jetting for the carbs will probably work for you. If you use the original manifold and/or stock cams, my jetting might help, but I predict you'll have to make changes. Frankly, jetting is probably the simplest part of this process.
To use the 45mm carbs, I had to "port" the OKP manifold to match the carbs. This was surprisingly easy, although it made a bit of a mess in my shop. I was completely satisfied with the smoothness of transition and flange-matching that I got. I spent a little time matching the interface between the manifold and cylinder head, but not as much as I might have done. Given the scope of work this entails, it probably makes sense to have your 102 head done by a professional shop that can clean up some of the airflow restrictions, and perhaps help with matching the intake ports to the manifold. As 102 heads are harder to find than OKP manifolds, I decided to leave this work alone. However, I do have a spare 102 head that I may tackle some day toward a few more foot-pounds of torque.
So - a proven "formula" is good to copy, so long as you copy all of the pieces. Once you start changing things, you are conducting your own experiment.
Carson City, NV
59 102 Touring (first Alfa $500 running)
65 Sprint GT (2nd Alfa, $500 daily driver)
102 Sprint (never did anything with it, but wish I had)
74 Berlina (first new car - now certainly rusted into oblivion)
61 Giulietta Spider G-Prod Race Car (where is it now?)
84 Spider Veloce (rarely drove it, so sold it)
86 Quadrifoglio (Dull car - no more 115s for me)
1971 Montreal "The Full Monty". Fair winds and following seas
59 102 Touring Roadster - restoration complete, enough Alfa for any rational man. Or irrational, for that matter
Two 1946 Stampe SV4C (c/n 294 "Rocinante" - wife's favorite airplane. RIP), and c/n 235 "La Bon Temps Femme" (gone to a new home, but never forgotten)
Zlin 50LA (+9 -6 gees, titanium spar, 1200 lbs, 260HP rumored to now be in Brazil)
1946 Luscombe 8A
Starduster Too (recently spotted at the Nevada City, CA airport - over 20 years and an entire continent separating it from our stewardship in Binghamton, NY)
1955 Cessna 170B (wife taught me to fly tailwheel in this)
64 Mooney M20E ("Rambo". My faithful steed for over 30 years) Nearly 50 years old, and just returned from a trip to Argentina in him
Newest in the fleet
1967 Piper Super Cub on Wipline amphibious floats (a true "all terrain vehicle")
2010 Triumph Thunderbird
You can snap roll an Alfa only one time...