Definitely clean a small section to see what you are dealing with before you submit a price.
We did a similar job this week that is part of a bigger contract, was probably the size of what you can see in your pic, took 2 men half a day. To look at looks easy but was hard graft so the money has to be right.
Stanley scraper, fresh blade and a bottle of white spirits to break down the residue. Not a waffle cloth in sight.