Drive line clearance

[Rwalkup]

Good morning, I am building a 1948 Chevy 3100. Put a 350 with a 350 transmission in it. I'm wondering how much clearance is a minimum for the driveline on the main center crossmember. I don't want to have to do any extra crossmember work if I don't have to. I have a static lowering job, drop axle in front with lowered springs and lowered springs and Blocks in back. Right now I have about 2 1/2 inches of clearance from the top of the driveline to my center crossmember that the center of cab sits on. Hopefully these pictures show up, this is my first post. Don't mind the broomstick, it was only way I could test my clearance before I got my driveline ordered. Thanks in advance for any of your suggestions.