If your options are thin for friends and family private money partners it would be worth your time to consider alternative strategies.

I've looked around as best I can and can find no other forms of alternative lending for a deal like this, wherein a buyer has a home under agreement that - by all accounts - is worth 170% more than the asking price!

One alternative is to talk to the bank to see if they would be willing to cur their losses now.  

im not sure which type of brick wall you are referring too, but framing wont vary much on cost for the same wall that is load bearing verses non load bearing. its more a function of materials and complexity. as for bundling, anything is negotiable. in general, i have found it much easier to negotiate with contractors for bigger versus smaller jobs. put yourself in their shoes, a bigger job has more security and profit. i would be willing to accept lower rates for a project that will take 4 weeks versus one that takes 2 days. 

If you delead, and maintain the standard, you will be in the clear.Here's the law (emphasis added by me):460.100: Duty of Owner(s) of Residential Premises (B) Whenever any residential premises containing dangerous levels of lead in paint, plaster or other accessible structural material undergoes a change of ownership and as a result a child younger than six years old will become or will continue to be a resident therein, the new owner shall have 90 days after becoming the owner to obtain a Letter of Full Compliance or a Letter of Interim Control, except that if a child younger than six years old who is lead poisoned resides therein, the owner shall not be eligible for interim control, unless the Director grants a waiver pursuant to 105 CMR 460.100(A)(3).

Alternatively, and I think this is the real issue, you are going to have to get over your fear of confronting this issue head-on.  

Who do you watch for any other RE related material?

@Adam D Rinehart $85-$90/sqft is good price but now with COVID cost has gone up so much on lumber and many other materials.

Now IF we had all the people in the world going to trade schools which are currently at about 5-10% enrollment of pre-collapse numbers, and IF we had every developer dripping in billions to start all the developments needed to get to parity now, IF we had magic wands to waive to make the ridiculous mountains of red tape disappear so it didnt's take ridiculous months on months to get permits to break ground, you'd still have to answer for the fact that we can't get lumber, decking, fasteners or really just name the material because there is the biggest materials shortage in recorded history, only WWII compares in material shortages and there is 0 relief on the horizon because there is still various covid shut downs and restrictions.

Maybe you can take a look at MF syndication or some alternatives?