You'll need one of these.
http://www.parts123.com/parts123/yb...~S3KG1A1PI663142223824g~Z5Z5Z5~Z5Z5Z50000132A
Once you pull your carpet, it's pretty self explanatory where it goes. I drew a line around mine with a sharpie, scribed another line 1-1/2 inches inside and cut the floor. I fastened the hump with some sealant and self tapping screws.
Your factory crossmember will work. You'll need a muncie with the correct tailshaft to mount the nova shifter and linkage with the speedo cable on the pass side. The nova shifter comes through the floor quite a bit further forward than many other GM applications.
Find pedals and clutch linkage from a donor car if possible. The aftermarket stuff will do, but the factory stuff is a bit better quality. Keep in mind that some headers are incompatible with the stock clutch linkage. Some folks have used a hydraulic cylinder and throwout bearing.
If you use the stock lingage, you'll need the nova specific bell housing or scattershield. The clutch fork comes out in the 7:00 position instead of 9:00 in most other GM applications.