If your bell housing is supported with a crossmember, then you can simply bolt your T5 to the bell. How is your current transmission supported?
I have a T5 in a 1963 C10, and also in my 1965 C10. Both of my trucks have a crossmember to support the bell housing and the T5 is simply bolted to the bell. So my T5 just hangs off the back of the bell, but that is fine for a daily driver. See photo.
The slip yoke for aT5 is very common. Your driveshaft will be about 3 inches shorter. I was able to find a driveshaft at the salvage yard with the correct slip yoke and the drive shaft length was correct for my application. A conversion universal joint at the rear of the shaft made it bolt to the rear axle. It was very simple to install.
Here is a page from my website which you may find helpful.
LINK HERE I show every step when I installed a T5 in my 1965 C10.