Home with 3.625%, trying to takeover mortgage, renovate/rent home and buy TX home

[Nick Victorio]

My parents are moving out of state and want to sell their home, but are willing to put title over to me if i can figure out some creative financing(Prop 13 advantage).  Which includes buying them a home in texas and paying it off so they have deed. ($250-$300k within 1 hour from temple,tx).   

The current home in San Diego County has a low 3.625% interest rate and low remaining principal of $89k , i would not want to refinance due to this great rate and proximity to my current home. Unfortunately, the house needs significant work done to allow it to be rented out, this has the potential of bringing in rental income of $3-5K a month.

After renovations, the home will have alot of equity based on the guestimated $100k-$150k renovation scope, (estimated ARV 800k). Based on capital and E1 zoning, I could add a guest house and more bed/baths to match the comps 1 block away: (5 bed 5 bath that are valued at $1.3-1.5 mil).

I have a primary residency and heloc on it, with $100k available.  So this limits my approval with additional loans i would assume.  Would anyone know what would be the best way to go about this? Or referrals for lenders, contractors that have dealt with this type of scenario.