Some inspiration for you. This is one of my most popular models. At the grade school presentations I do I let the kids power the engine and they love it. While walking around engine shows, pull it out of your shirt pocket and impress the guys building stuff with valves bigger than your engine.
(https://www.use.com/images/s_2/4f3c05b38e466e5bf627_50.jpg) (https://www.use.com/4f3c05b38e466e5bf627?p=50)
(https://www.use.com/images/clicklarge3.gif) (https://www.use.com/4f3c05b38e466e5bf627?p=50)
(https://www.use.com/images/s_2/4f3c05b38e466e5bf627_51.jpg) (https://www.use.com/4f3c05b38e466e5bf627?p=51)
(https://www.use.com/images/clicklarge3.gif) (https://www.use.com/4f3c05b38e466e5bf627?p=51)
I suggest you make a longer blowpipe (mine is six inches) so you can see the engine operating when blowing it yourself. I've never found an oil light enough and so lubricate it with kerosene which, upon evaporation, leaves behind the mere hint of an oily surface. (Old timers lubricated their pocket watches by putting a drop of kero on the inside of the back cover.)
Don't forget to add the power takeoff pulley as I did on mine. I've led several people down the path convincing them that I actually power miniature machines with that pulley. :-)