The 700 series reels stopped at 707. Penn produced many more models besides those you listed. The number has nothing to do with the size of the reel. For instance, a 706 is larger than a 704, but a 716 is smaller than both.
The 714,716,720,722, were small freshwater reels. The 716 ultrasport was Penns smallest spinning reel, followed by the 714 Ultralight, slightly larger. The 720 and 722 both came with aliminum spools and were offered with aluminum side plates ot medallion side plates.
The 710 and 712 were considered both fresh and saltwater reels. The 712 had a smaller spool and it came aluminum. The 710 had a larger plastic spool.
The larger 700/701 was the first surf casting reel. It came out in 1961 with a solid handle, soon to be replaced with a folding handle. The 700 and the 701 was the same reel but the 701 offered a second spool. The 702 was a left handed version of the 700. The 704 and 706 replaced the 700. The 704 can standard with a bail, and was also offered with a solid aluminum side plate or a medallion plate. The 706 came bailless, with a coffee grinder handle. The 705 was a left handed version of the 704. The 707 was a left handed version of the 706.
Not all of the above listed 700 series reels were produced in the "Z" series. The first "Z" series came with black spools and black torpedo handles, the next generation of "Z's" came with gold annodized spools and handle arms.