you can go 30-30 altho you should go the minimum required to create round journals and fit the bearing sizes available. That way you may be able to do it again.
The filets are there to prevent stress risers at the intersection of the journal with the sides of the throws. They are rolled in. Turning the crank should not affect the filets.
On your other question, there are a lot of 4.1 blocks out there. Mike S. (Orlando87) can give you the story on 4.1s.
The filets are there to prevent stress risers at the intersection of the journal with the sides of the throws. They are rolled in. Turning the crank should not affect the filets.
On your other question, there are a lot of 4.1 blocks out there. Mike S. (Orlando87) can give you the story on 4.1s.