Dave,
I just recently purchased an Finex FX100 and have used it quite a bit in the last few days painting brackets ,etc. It's a very nice gun for the money and sprays real nice. It might be a little small for your needs though. I've also used the DeVilbiss Finish Line gun with a small compressor like you have with good results. Would probably work better for painting larger items like your frame and inner fenders.The little touch up gun,although it could do the job, would be tedious, especially having to refill the small cup continuously. Sharpe also has an FX200 and 300 gun though I have no experience with them.

Bob