I dont think I can help too much with the Zip, but I do like the idea of making a tire burner out of a Vicky.
Little different principle.
The car and most modern saws suffer from a modern problem. That being environmental and safety limitations imposed by the government. Getting extra power from newer stuff is as simple as defeating the regulatory stuff and letting it run as it was originally designed. Let it have more air, more fuel, and let the exhaust breath freely. More open heads on the 5.0 and maybe a more aggresive cam. Open exhaust system. Same as porting a saw with timing corrections and doing a muffler mod.
Older saws like the zip are a different story maybe. They were built before the environmental limitations.
They were limited by the strength and quality of the components they were built from. Newer technology allows for longer life, due to better alloys and protective coatings.
Not saying your saw wouldnt benefit from some port work and a timing advance, followed by a carb that gives it more fuel. The problem might be in whether or not the cylinder, piston, and bearings of the reciprocating assembly can handle this added power and speed.
Like adding nitrous to a stock flathead Ford Motor. Might be awesome for 9.2 seconds, then its gonna be expensive.
Theres a lot of people on here with way more knowledge than me that can lead you in the right direction. Just putting in my 2 cents worth for thought.
