10 Series Briggs Flathead

[The.MiniTard]

Okay so I have an old 4 hp Briggs and Stratton engine that I will be using to power a minibike for myself(6'2'' 230). Not really worried about performance with this engine, i'll be gettin a 5 hp for that.
I'm having trouble identifying exactly which 10 series this engine is.....I've taken the head to check bore and stroke and i've come to a tad under 2.5'' bore and a tad over 2'' stroke(i dont have precise measuring tools).

If anyone can find out anything with that info I would really appreciate it.
Also....what in the hecka is going on with these valves on this block they look slanted and why is that area cut like that around the valves?

 

[ezcome-ezgo]

What does the cylinder head have to do with bore and stroke?

 

[OzFab]

I can't see pics; please revise...

What does the cylinder head have to do with bore and stroke?

Well, you would need to remove the head to measure the bore & stroke...

 

[landuse]

Pics not there for me either. I see the following:

 

[mckutzy]

Photobucket is doing hosting anymore, they prefer to gouge people instead... Not anything reasonably priced either...