How far in should the Slip Yoke be....904

I am getting the measurment for the new drive shaft. Have a 904 and will have 1350 joints. Most everything I have read says to shove it all the way in to bottom out and then pull out about 3/4 to 1". The rear seal has the normal extended boot on it and I can push the yoke till the start of the radius of the yoke just touches the seal boot portion, but then you can shove it in even further to actually bottom the yoke in the tranny. If I push it all the way to bottom in the tranny and then pull out the 3/4 to 1", it will still have the boot collapsed somewhat. Appreciate your thoughts. BTW the yoke is a Mark Williams unit.