Yes, the 5 speed from a 16V will bolt onto an 8V. You will have to replace the auto flexplate with a flywheel and clutch, of course.
The 5 speed probably has braces that run from the engine to the bellhousing (one on each side of the engine). You may or may not be able to use these on the 8V (depending on if the 8V has places to bolt them on). If it doesn't, then just leave them off.