Tim,
That's a low hump cab. If it doesn't bolt in, and is essentially part of the cab floor, it's a low-hump.
If it bolts in, it's a high-hump, which was used by GM to clear larger drivetrain components. There are several different varieties - one round hole forward for 4spd, no hole for BB/Turbo400, dual holes for tranny and transfer case levers, one hole rearward for transfer case lever on auto trannys, etc.
Randy's thread
here shows several pics of the most common high-hump, the one for a 4spd manual:
This would probably give you more than enough room. Just cut the floor out using the new hump for a template and bolt it in. I used silicone to seal it up. You will need a different floormat/carpet, tho.
SSOW
