Welcome to GTT, Garrett !
The Bolens Model 12BB-01 tractors were made in 1950, 1951, 1952, & 1953, and are known as Power-Ho tractors. ....Here is a manual for the tractor:
Here is a link to the Power Ho section of the Bolens Manuals where many PowerHo attachment manuals can be found:
The Manuals Forum here at GTT has a library of many manuals for many brands of equipment & engines. ....There is a tab for the Manuals forum at the top of the page (just under the GT Talk heading).
The B&S Model 8R6 engine was most common on a Bolens 12BB01, yet some 12BB's had B&S NPR6 engines. .....There should be a metal plate covering the cooling fins at the back-side of the engine. ...The B&S Model, Type, and Serial numbers are stamped into that plate (if it is still there).
Here is a link to a B&S Repair Manual which will cover your B&S engine.
Here is a B&S manual for the Model 8R6 engines. ....Your B&S TYPE number may, or may not, be covered by this manual.
There is a limit to how many manuals you can download on each visit to GTT, so you may have to spread your downloads over several visits. ...Of course, any downloads are FREE!