Louis, the question you ask about the engineers is one that probably could be answered best by Ken Noe
Steve Ruby I'm sure would have a better off the cuff answer as well.
Clarence Brent and Robert Casebeer were both engineers with the Helio factory. I think Clarence was the Chief engineer.
I believe that Clarence continued working on the Helio after the factory closed the first time as an independent engineer and Robert Casebeer worked for Helio Enterprises inc.
I think they both worked on the type certificate for the H-7/800.
Clarence developed some oher Helio STCs (now owned by Gordon Cragg) and He was the engineer that worked on H-5 (the low time Helio you speak of), H-5 was used for some gear leg drop tests. H-5 was also used to develope some speed mods Wheel pants and a modified cowling that reduced drag and gave better cooling I don,t believe Clarence ever got aroun to sumitting the paperwork. I believe it was owned by Luigi Chinetti when you saw H-5.
see H-5 here
http://flyhelio.com/smf/index.php?topic=1230.msg4722#msg4722As far as the automootive fuel that I sometimes carried in myoutboard tanks for snowmobiles, chainsaws whatever was the automotive fueland that was available on Merrill field Anchorage for A/C STCed for automotive fuel. I also flew ultralights and had a couple engine failures before figuring out 2 cycle engines are highly prone to lead fouling when you use 100LL or even 80/86 avgas.
I could if needed burn the autogas in the GO-480. A few times when AV gas was difficult to find out in the bush I did use some autofuel usually mixed 50/50 with avgas. I also tried to avoid high altitude and high performance useage with auofuel.
I will give ken Noe a call, maybe add to this.