Welcome to 700Rifle and hope you will enjoy it here 
ok for the scope base you can look at the EGW 0 MOA or the EGW 20 MOA there real good for the price........
and from what i read the 30mm scope tubes have more field of view over the 1"
as for the actions well the .308 is a short action because its a shorter round the 3-06 is a long action because its a longer shell....
the .338 Lapua is a long action, the .243 is a short action .................... its pretty much based on the type of round you want to shoot
is what will change the action from short to long or long to short...... now you cant modify a action to make a long or short...... but you can do this
like the Army's M24 it has a long action with a .308 chamber and running .308 indstead of a longer round like the 30-06 or the .338 Lapua.
ok for the scope base you can look at the EGW 0 MOA or the EGW 20 MOA there real good for the price........
and from what i read the 30mm scope tubes have more field of view over the 1"
as for the actions well the .308 is a short action because its a shorter round the 3-06 is a long action because its a longer shell....
the .338 Lapua is a long action, the .243 is a short action .................... its pretty much based on the type of round you want to shoot
is what will change the action from short to long or long to short...... now you cant modify a action to make a long or short...... but you can do this
like the Army's M24 it has a long action with a .308 chamber and running .308 indstead of a longer round like the 30-06 or the .338 Lapua.