Why standard bore? I would expect a bore job to oversize to be cheaper than a sleeve job to standard because of fitting of the sleeves and cost of sleeves. You'd old pistons will have wear in the ring lands. Your old pistons are low compression also.
My suggestion would be to bore to whatever cleans up your block then buy a new piston kit which will be high compression. The new pistons will offer more power and higher efficiency. You can make 5-7 more hp on the same amount of fuel.
You'll also want to get some new wrist pin bushings installed and fitted to your new piston pins.
While you have that head off you might as well have it checked for flatness and have valve seats installed with new valves. It'll keep you from having to open that engine back up for many years to come.
For efficiency and power I would also suggest a gasoline manifold.
With all these improvements the early B may get close to late B horsepower. Most of these suggestions are efficiency improvements. Your B can make 18 HP all day on 25 gallons of gas or 25-30 HP all day on 25 gal of gas, depending on which parts are installed in your engine.