The converted knuck heads I've seen all used a new port out to the left, horizontal, and parallel to the crank axis (and each other). The interior work to form the new bowl and close up the old port is generally not very clean, and very few look like they were flowed so there is definitely more power there. I don't think that's the best entry point, but it's difficult to do over.
IIRC the vintage rules say the carburetor must be primarily of motorcycle design, but evidently very little attention is paid to this because there is a H-D with a record using a Dell'Orto DHLA.
Bore and stroke is a puzzle, because the original rockers are both low ratio and heavy. De-stroking to raise RPM is going to need some re-work there (IMHO). Pete Hill made a knuck drag motor with the entire pan rocker box assembly on it (far easier to adjust an set geometry, higher ratio, can be purchased as a roller tip conversion from Baisley), may be legal since the pan parts are all pre-1956.
The shortest stroke commercially available TIKO is 3.500" (stock EL, but with the big pin). An EL just isn't going to like 7K rpm.
You have a compression problem due to dome intrusion, especially with small displacement. The dome volume and shape are much better with big motors. The fix for pan and shovel is to bath-tub the chamber (much harder with cast iron), and you're still stuck with the Jaguar/Chrysler vintage huge included angle (80°), so the chamber can't really be flattened.
