Family (Uncle) wants to sell me their home

[Jay G.]

My uncle approached me to purchase his primary home....

SUMMARY:

• Home might be FMV $430k+ if it were in good condition
• Home needs some significant repairs (leaking roof, ground settling, cracks - 100 year old house) 
• Only major update was HVAC system 15+ years ago.
• Family member would sell it to me $300k as-is
• Home assessed at approx $160k right now
• It's been his primary residence for decades  - he'll walk away with his $250k tax free capital gain.
• It would become my primary home after 4-6 months of rehab (currently renting, but we sold a home exemption qualifying primary this year as well)
• Uncle is the kind of guy who will give *someone* a fantastic deal on it (because it needs some big work) - so why not me? Also we'll be saving those agent commissions/markups. 

QUESTIONS:

1. Is there any way to preserve that tax assessment through some kind of "family" transfer? (Assuming NO here... since Uncle)
   
2. In case of "NO" above - if the county assesses a value higher than my purchase price, then.... (could this affect #4?)
3. Does the IRS (or lenders?) consider an Uncle a "related person" ? or non-arms length transaction?  ( looked around publication 544 where they have a definition - and Uncle/Aunt/Niece/Nephew seems excluded here, but I've seen them listed in other sections before)
4. If I got an appraisal and inspection and it came in over the $300k he would sell it to me - say $375k - could this trigger tax issues? (E.g. claims of equity gifting to me, or under/unreported gains to him, etc.)
5. We'll definitely be putting $50k-$100k additional into a small addition, and total rehab. I would imagine this could also help "justify" any perception (on paper) of selling a house for a "very good deal"  ?

Asking here because very interested in proceeding, but I like to keep things on the up and up (no headaches, no nightmares)

I definitely don't want to leave any money on the table though. :)