I have been able to find the dimensions of the pan, but not of the cake itself or 2 parts. 

I realize it will vary according to frosting, etc.  

Can someone tell me approx. how big the baked cupcake is?  Is it comparable to a 6" , an 8"?

It says it's a 10-cup capacity (in total), and that is more than what I would put in 2 8" rounds to get a 2 layer cake.

Nordic Ware also do a pan like this, and says it's 6 cups, which is less than what I would put in an 8" but more than a 6" . I just baked one today in fact. Since I borrowed both pans from someone, I am going to try the Wilton one tomorrow cos the NW one is just a bit too small for me.
 

AOh thank you so much! By any chance can you measure the diameter of the bottom. I need to know what size cake it can safely be placed on top.

I'll measure them both tomorrow, no problem. But just looking at the Wilton pan, I would say it would look better on top of an 8". NW one would look good on a 6" but the Wilton one is a bit big for 6" IMO. I'll check tomorrow ;)
 

I baked one and put it on a 6" cake board. It was small and I wound up cutting over an inch off the board.. The outside base is 4&3/4", inside base is 4&1/2". It tapers up to 6". This is the Wilton pan. I don't have the other pan to compare. HTH

I think it would look better on an 8" cake since the top of the cupcake is almost 6" it would be the same size as the 6" cake that it's sitting on.

Firstly, apologies, because this morning I realised I didn't have the Wilton pan, they are both NW Anyway, in case its any help, attached are 2 pics of the baked cupcakes, on an 8" dummy. Bear in mind they are not filled or decorated which would add height and width. The smallest one (6 cups batter) has a 4" base approx, and the larger one (10 cups batter) has a 6" base approx.
 

http://www.nordicware.com/store/products/detail/pro-cast-cute-cupcake-pan/DF2A1462-600B-102D-B5EF-00137233C6B0

http://www.williams-sonoma.com/products/the-great-cupcake-cake-pan/

The smaller one looks nicer on the 8", the larger cake would look better on a 10" I think. Since the Wilton mold is 10 cups, I think it will be a similar baked size to the large 10 cup NW pan in the second photo.
 

AYou guys Roxers!!

This is for a birthday cake, & I'm thinking of puttin the cupcake on a 2" thick large cake & decorate like a table top. I needed to know dimensions to get the correct proportions.

Seriously, you guys are so wonderful to help!

No problem, good luck!