Also needing a driveshaft

[Korted]

I have read quite a few threads here about driveshafts. One common recommendation is not to trust anyone else's measurements, as all installations are a little different. I hate to ask the same questions as previous threads, but my case is a little different than any I have read. Here is what I have:

2000 LM7 with 4L60E swapped into LWB 1968 C10 with coil springs. trans is mounted to stock 1968 crossmember with 2000 isolator.
Distance from back face of 4L60E tailhousing to center of diff u-joint = 71.25"
At normal stance, measurement from centerline (trans output to diff u-joint) to bottom of crossmember is 2.25"
Distance from 4L60E tailhousing to crossmember is ~30", crossmember to axle is ~50"

If I use a 3" 1-piece driveshaft, I will have 0.75" clearance at normal stance, and will not hit the crossmember until the axle drops 1.25".

Is this enough clearance? I like the simplicity of a 1-piece driveshaft, but am not sure it's the right way to go. TIA for the input. The information here has been invaluable so far, and I'm sure someone out there has recommendations for this one as well. Thanks!