I think you are going to need more convertor than 2500rpm.

Your grind is very similar to the Crane 302 H06 grind which is a Hydraulic lift grind with .500 lift and the same duration as yours. Crane recommends a 3500+ stall convertor for their grind and 10.5-12:1 compression.
How large were the combustion chambers in your old heads? How much compression are you going to have with the 64cc chambers? What ratio gear is in your rear axle?
The bumpstick is recommended for 262-400 cubic inch small blocks so I think you will be okay with the 350.
Remember, when you see all of those off the shelf-brown bag convertors in Summit from TCI or B&M, the stall rating is behind a more torque producing big block, not a small block. So if you bought a 2500 stall (which might stall at 2000 if you aren't making adequate torque) your car may be a super pig and wouldn't accelerate worth a damn,

considering the vehicle's weight.
i wouldn't worry about rockers and all that other jazz, you need to make sure the basic combination is right.
"ein 750cfm Vergaser sollte dann wohl auch drauf" -Too big especially if you go for a 4150 DP, if you were to use a 3310 vacuum secondary type it would probably never fully open. We ran 11's on a 600cfm and 700cfm DP with a 385ci and a mechanical fuel pump.
We've got a used TCI Super Street fighter if your interested. Stalls a little higher.