[Zeke]

You may be able to place new columns at 8 to 10 foot spacing, add the vertical and tie some horizontal to the columns at the existing height. As it is, you are no where near the code requirements for steel and footings.

If you are anywhere near Garden Grove, stop by B.C. Adams Engineering (civil) and ask if they have done anything like this. In the 50 years they have been there for the pool, fence and patio cover trades, they have seen it all. They are very homeowner friendly and quite reasonable.

Frankly, I think I'd start over and get an all new wall for the price you can get it for nowadays. In Long Beach, I tell folks to plan on 80 to 100 per foot for everything in the back on the property line for a 6'6" x 6" block.