If you develop a great relationship with local credit unions, you'll be surprised by what all they're capable of.   

and how well my credit score will be?

Your best bet for that size will be local banks and credit unions, good luck.

We have credit scores over 730 and have been "soft approved" for around $750k. 

The seller doesn’t need to know that the underwriters may give you more of a hassle than other buyers.Or do you have lines of credit or a private lender so you can make a “cash” offer then try to get the financing through before close or at worst just do a cash out refi after close?

As mentioned seller credits are the best path as title insurance and taxes are pretty much fixed.

Does anyone utilize a line of credit as an emergency fund?

I went to my local credit union, Wells Fargo, and United Bank and each one turned me down after "checking with legal."  

Hi Nate - It'd be worth asking the lender for a detailed breakdown of closing costs for this program, as well as an estimate of the interest rate you'd get with today's rates (they'll probably need to pull your credit to do this).

I have been battling with the credit bureaus for 15 years between 2 divorces, and multiple incidents of identity theft (the untold effect of military service).