That engine was quite a terror to break in (I remember mine was). Here are a few general tips that you may or may not know.

- use a hotter glowplug. unfortunately the novarossi/rb/novamega line of plugs was originally designed for bigblock engines and so the temp range is colder than what is needed for our small blocks. if its still being finicky go back to a number 5 plug.

- preheat the engine with blowdryer/heat gun at low setting. i remember my RS12S5 having a very tight piston/sleeve set. preheating it should loosen it slightly for a easier startup/breakin.

- 240 degrees doesnt sound that bad if its operating temp, but if it is stalling/flaming out then you should richen your main needle.

- 20% is 20%. IMO fuel preferences is just that, preference. Just make sure you got a fresh bottle as old fuel will add to your headache.