First and always, the rules are posted on the web. If you can read my opinion of what the rules may be, you can read the actual rules themselves:
http://pampacl.org/resources/documents/pampa-forms-rules-and-scoresheets.html.
Second, it's a 10 point bonus for a sparkie, but it can't just be any old glow engine converted to spark: it has to be a gin-ewe-wine original or an approved reproduction -- no converting an OS 46LA to spark and beating up the competition.
Mostly people run spark because they want to preserve the really old stuff -- the bonus is just a "thank you".
Third, it's not an official event, so your local contest may be different -- ask, or if you have some regional organization, check their web site.
Unless your Webras are real fuel hogs, 4oz should be enough -- the OTS pattern is shorter than the current AMA pattern.