Just a quick thought about this is that the 45mm is just enough to feed both cylinders at once.
With a blower on it, you can make it bigger and not suffer
However, the cylinders feed on different strokes, so technically you would never have to feed them both at the same time. So the size could technically be smaller.
As long as you have enough plenum volume, and boost, that should feed plenty. If you feel more comfortable with bigger, then it shouldn't hurt anything when there is boost coming in from the blower.
Even though we don't have flow numbers yet, that size port is likely to flow near what the Fireball flows. So probably a little less than 200 cfm per intake.
Maybe 50% more than that for boost, so seat of the pants figure 300 cfm for each intake, so max blower output of 600 cfm. Theoretical 150 hp potential at those figures, if it could be attained and hold together. Not sure it would. But it might. It' s not having to run for very long.
The 50mm could theoretically flow 444 cfm normally aspirated and uncompressed. That's more than double what each port would flow normally aspirated. Compressed would flow more.