From what I've discovered there are really two main types of Tyvek: hard-structure and soft-structure. The numbers you refer to are variations in applications of the two types. Hard-structure, type 10, is most commonly recognizable in the housewrap application and is suitable for a ground cloth. It is stiff, noisy, and loud but that can be remedied. Soft-structure has two main varieties: types 14 and 16. Type 16 (1622E, 1673) is not suitable for a groundcloth as it has lots of tiny holes in it. Type 14 (1443R) has a soft hand and is just as water resistant as type 10 (10G or 10GX) so either type 10 or 14 will work for your application.
I might recommend the hard-type as it will be easier to lay out your groundcloth to cut and measure. After you have completed it you can then wash it several times to soften it and make it more manageable. It also will be easier to find as you can get it at both Lowe's and Home Depot. However, I don't know if you can buy small quantities there. You also might check construction job sites (with permission) as they often have some left over that they just throw away. I got almost 30 yards of good Tyvek this way because they had tossed it.
Here are some good resources for more in-depth information:
The Definitive Tyvek Article