If you buy STS, you can buy the extra back plate or roto start plate to replace the pullstart. The engine was way too tight for pullstart. Starter Box or rotostart is the way to go!!
Brother f60, STS .28 engine lah.............I am using this and it is my first engine. I just ran in the engine for 2L fuel, so far so good. I took apart the engine and it looks very good.
If you go for the STS, make sure you buy the new version wor.