What is the 340 gasket bore in inches?

Watch out!
Check out the method of determining the ICA; they use the 050 number plus 15*. That is not right. Or at least not right for a flat tappet hydraulic.

Here is a comparison. I have a 276/286/110 cam in at 106.
The 050 numbers are 230/237/110

This cam has an ICA of 64* using the advertised.
It has an ICA of 41* using the 050 numbers.
Adding 15* to 41* equals 56*.
This is 8 degrees short, and this will throw your Dcr waaaaaay off, right into soggy bottom end territory, if you are not careful.

Also, be very careful to enter your piston pop-up or dish correctly, as a plus or a minus.