Hi Frank,
There has been some good thoughts given to you so far. May I suggest the easiest way for you to learn about pines is to buy this book
http://www.stonelantern.com/Pines_p/b1pine.htm
Asking on the forums is an ok way to learn a thing or 2, but you won't learn as much if you just bought the book. Right now it is about the best book on pines that I have found.
As for your tree, yes, this all depends on how big of a tree you want, etc??? So with out knowing that I did a quick drawing using Paint. There are many options for this tree, the one I instantly saw the other day when I looked at your post was this one, the one in the pic. You could graft on to it, but really I think that would only be a learning tool.
So, the red lines are what I would cut back to on the tree. The green arrow is the branch I would let grow freely. As it it gets taller and send out side branches I would cut those side branches off and only keep the ones up higher on the sacrafice leader. When you get the desired trunk girth and tree size then cut that whole branch off.
The green is one option you could do with the tree you have now. If you wanted it taller then simply let it grow and train it as it grows, but while pliable. For details on this the book will help you out and let you know what you need to do and when.
But really this tree is a blank slate, it will back bud if pruned, pinched and fed right. We hav JBP with 8 inch trunks in the field that will throw buds like crazy on the old gnarly barked up trunk.....even bud off the trunk down at the ground! If you can get yours to respond like that then the options are endless.
The best advice I can give you is order that book!
Good luck, Jason