I have been looking at the Scale Dreams website and they look like they have a lot of products that I could use, you might want to check them out. Tower hobbies is good too.
One of my first "modified" builds was a 32 ford sedan. It was a really nice kit and it taught me a lot about detailing and customizing a model. I would suggest getting a 32 or 34 ford and building a "Rat" to start off with because you have alot to work with ( options such as lowering and getting stances right). You also have alot of "room" as in on the engine and on the frame.
Heres my sedan :
Its not my best but I really had a lot of fun building it, and I learned alot
It was my first one that I wired, the first I lowered, and the first I used parts from other kits to build. You may or may not like rat rods or hot rods, but they sure do have a lot of room to work with.
Good luck !!!