Bbc holes are out around and upper than sbc.
My old sbc have spacer between riser and manifold. So now bbc height is right with those holes that i have, but bbc exhaust is 5cm (2") wider than sbc/side.
With sbc i have Alpha, but now i have Bravo1 with bravo exhaust y-pipe.
I have silent choice, what is best option for me?

My friend have 4" stainless steel (idont know what english word is for these) but pipes that change centerline 2". But its hard to fit them any place. And they are 114.3mm, and my exhaust only 101.00mm.
those pipes are 5" long in picture.

Custom built offset tubes to align with the transom exhausts..

youre looking for these, if you are making the exhaust 3"..
(On swedish, but excentric cone in english)
https://www.dahl.se/produkt/kona-exc...76-316l-282271

I made these when I switched to higher exhaust, it all depends on space.

Making an offset in that short of length is going to be a challenge. I think I would fill the transom and and recut the holes. Stainless Marine manifolds might ease your pain a bit if you are set on keeping your existing exhaust exits - the risers have some side to side adjustment.