Full disclosure I help dispo deals for REI Nation who operates in several markets in the southern/middle part of the country. 70% of the sales go to existing clients so I think that speaks volumes to those investors experience. 

Though, don't be discouraged because these deals do exist and are still out there.

Also, to give you an idea of how the math works here is an example based on your home's values:If the lender lends up to 80% of the home's value, the maximum loan amount based on 80% LTV would be $392,000 = ($490,000 * 0.80).With your existing mortgage balance of $390,000, the remaining available equity for the HELOC would be $2,000 = ($392,000 - $390,000).Hope this helps!

Does such a conversion exist?

Can an acquisition help an existing portfolio? 

Ike - I'm with Doug on this one.Credit Unions / Local / Regionals are great if you have a pre-existing relationships.

Check with a RE attorney, but I've always heard that if it was existing it is grandfathered in - as far as the Code is concerned - Liability I'm not sure. probably not.....

Right now the median price of new construction homes is as close as I have ever seen it to the median price of existing inventory. 

But when I followed the link provided inside the book and entered my email address, it says "... the page doesn't actually exist".

It simply does not exist.