On that deal I would go with either the Jesel paired shaft set up or the T&D paired shaft set up with 1.7 or higher ratio rockers with a custom ground cam for the RPM you want to shift at
I advise all my customers to stay under 8000 RPM on most BB motors I build, I say that due to not having any real hands on experience with a motor shifted above 8000 RPM yet.
I have most of the parts to build a 555 C.I. B1-MC headed motor with a Koleno high nickel iron block with a good rocker arm set up like mentioned above. Most of the B1-MC motors I have heard of like to be shifted around 8600 RPM
My current bracket motor with the Jesel set up with 1.55 ratio rockers has not been shifted above 7200 RPM so far, I will experiment with different shift points on it later this year. I've had it out four times so far and have not had the time at the track to try shifting it higher yet do to other new motor issues including ignition problems with E85 at 15.0 to 1 compression ratio
I really like the Jesel set up as it is easily adjustable on the height of the paired shaft set up to correct the geometry Not cheap though, mine was included on a pair of Indy 440-1 heads I bought so I had nothing to do with the ratio on them.
Go with steel rocker arm kit, not aluminum now
This motor has right at 325 lbs. on the seat pressure and a little over 875 Lbs. over the nose, on the engine stand it turns over really smoothly once you get it turning ,not like all the other motors that I have built with the single shaft set ups with similar spring pressures
Good luck on your deal