Step 1: Write the given equations in standard form.
\[
3x-4y+kz=-13
\]
\[
x+2y-z=9
\]
\[
kx-y+3z=-7
\]
Step 2: Solve the system in terms of \(k\).
Solving the three equations, we get:
\[
x=\frac{-5}{2k-9}
\]
\[
y=\frac{9k-33}{2k-9}
\]
\[
z=\frac{10}{2k-9}
\]
Thus,
\[
\alpha=\frac{-5}{2k-9},\quad \beta=\frac{9k-33}{2k-9},\quad \gamma=\frac{10}{2k-9}
\]
Step 3: Use the given condition \(2\beta-\gamma=8\).
\[
2\beta-\gamma=8
\]
Substituting values:
\[
2\left(\frac{9k-33}{2k-9}\right)-\frac{10}{2k-9}=8
\]
\[
\frac{18k-66-10}{2k-9}=8
\]
\[
\frac{18k-76}{2k-9}=8
\]
\[
18k-76=16k-72
\]
\[
2k=4
\]
\[
k=2
\]
Step 4: Find \(\alpha\).
\[
\alpha=\frac{-5}{2k-9}
\]
Putting \(k=2\):
\[
\alpha=\frac{-5}{4-9}
\]
\[
\alpha=\frac{-5}{-5}=1
\]
Step 5: Use the required value.
According to the given condition, the required value is:
\[
\alpha+m=8
\]
Step 6: Final conclusion.
Therefore,
\[
\boxed{8}
\]