Hi,

At first, you need to find out the relationship between the one drawing unit and real world unit.
The second - you need to decide which drawing space you will use for output to paper at 1:50 scale - Model or Paper space.

For example if 1 drawing unit equals 1 mm in real world and you want to output the drawing from Model space at 1:50 scale, than you need to scale up the Title block 50 times when you insert it to the model space. Note: I assume also that Title block you want to insert was created at 1:1 scale, i.e. 1 unit in Title block = 1 mm .

Maxim