After a couple of thoughts, tests and trials, I've come to a dilemma...
1) Keep the RC's OEM triples and just have them bored to the Ohlins 56/51mm fork diameter?
That way I can keep the original RC's 213mm offset and the Honda look on the upper one which I adore.
Having the RC's OEM lower/upper triples bored at 56/51mm is not much of a trouble.
The differences are minimal and as I see it, milling 2mm of aluminum on each of the lower triple fork's holes won't effect the structure's strength.
The material in black will be removed
2) Have a lower triple's spindle made, copying the RC's OEM one, and have it pressed in the Ohlins' lower yoke so that it can fit on the frame.
That way though, I must use the Aprilia upper triple due to the 10mm shorter offset which makes the Aprilia lower and the Honda upper triples incompatible. Showa's (OEM) offset is 213mm.