The Model tells us it is 9 cubic inches (148 cc), of the second design generation, with a horizontal crankshaft, a Pulsa-Jet carburetor (hence it has a fuel pump, with a diaphragm: the Vacu-Jet version had neither), plain main bearings, and a rewind starter.
I can't find any information on Type 1025, but since you have the parts you need that should not be a problem at present.
The Code tells us your engine was made on 5 December 1997, which as you have observed, is quite a bit more recent than the production of the SB33.
Does the engine blow smoke, either on start-up or when running under load? Does it use oil? You have said that after each repair the engine runs "better", but not that it runs "well". Those Briggs engines normally run quite well - nothing comparable with a Honda or chonda, but it should be very easy to start hot or cold, and it should be quiet and reliable.
