We already have access to a HELOC up to $150k at 6.15% variable, but we carry a balance (that we're paying down) of $30k.

Nurture those seeds/relationships until they can bare fruit.

Payoff you credit card and don’t carry Cc debt.

These loans offer quick approval and fast payout, but they carry higher interest rates since they’re unsecured.Secured loan.

Despite those issues, the lender required us to carry both builder’s risk and general liability policies for the duration of the loan, which ended up being nine-months.  

If you sell for $700k, subtract 6% for selling/closing costs (maybe lower if you get your buyer's agent to list for 1%) = $658,000 -  12,000 ($4,000/mo for carrying costs (x 3 months)) - $80k in repairs = $566,000 is what you net.

There are Pros and Cons to carrying it personally (many people would tell you to carry as many as you can through Fanny and Freddie , because you typically get bett rates 30 year Ams), but personally I prefer to deal on the commercial side of things.I would reccomend that you reach out and get to know some local commercial lenders and see what they can do for you for loans.You should be able to get something between 4.5 & 5% ammed out over 20-25 years.I would encourage to not talk to your agent about loans.

The longer an investor takes to bring a project to completion the more the HML fees can eat into profits and more carrying costs can increase. 

I know you mentioned the condition, but the location carries a heavier weight. 

I might add a wall or cut a wall out to frame in a quick closet to claim a room as a bedroom but don't get carried away with it.