To be quite honest the formation of your letter strikes me more as an advertisement than a business proposition.

It's part of my unique selling proposition:  No need to show me the property.  

My proposition was to tie up the property under contract for 30 days with an agreed price that they were asking, market the property to find a buyer that would pay a little more, assign my interest to that buyer, and everyone would walk away happy.

I am sure you will find a banker that sees the value of the proposition and plan and want to get on board with you!

The owner has offered a non set in stone proposition that he would be comfortable selling it to me via a vendor take back deal at 550k and that i can do a 10% down payment at 5% interest.

Building vertical creates value with finished homes.It is imperative that all 3 of the above value propositions be properly calculated and maintained throughout the entitlement process to ensure that there is enough "meat left on the bone" for each level of development even if you are not planning to do all 3 yourself.Feel free to DM me and I will send you an intake form that you can fill out.

Would probably involve putting in a permanent foundation, and re-siding the home at least (probably getting a permit for a remodel) - not an inexpensive proposition. 

How would you approach a seller with this sort of proposition?

@Lisa Caracciolo looks like a money losing proposition.

“In my Inaugural I laid down the simple proposition that nobody is going to starve in this country.