If I had an answer to my money issue then I would quickly pull the trigger on a good deal. 

I appreciate your answers and advice in advance! 

I would call or email a specialist in FIRPTA such as "Tax solutions FIRPTA consulting" in Katy Texas, since they can answers all questions about the law plus investor friendly lenders

That's the question that needs answered.

@Cody Caswell there's several things to ask about here that might not be answerable in a forum:- Why do you need an FHA loan?

The short answer is No, you don't need it.

Short Answer is yes, via interest tracing rules. 

@Tobi Isaacs this would be better answered by other investors in your market. 

I was going to look over your numbers for you, but can you answer a few questions:* In what zip code is this property located?

Answer sure.. have to check if there is a due on sale clause or if you have a PG to the orignal seller.. that mortgage stays in your name unless there is a formal assumption  Maybe the example is more challenging for a house as the property.Ex. with vacant land - seller finances to me $20k with 5% down and $1k/moCan I after 1-2 months, then resell the land to a cash buyer for $25k, pay off the original $20k and pocket the $5k?