I checked the approved list for Swift UL 94 Fuel and it says the Skyhawk XP is approved. The Compression ratio of the Continental engine is 8 1/2 to 1. That also is the same compression ratio of my Skyhawk, but it is a Lycoming engine and it also is on the list. The only Skyhawk not on the Swift UL 94 approved list is the AD Engine Skyhawk With the 9 to 1 compression ratio.
That Engine was made starting in 1977 for a few years then it was changed to A different version of the 0-320 Lycoming, which had an 8 1/2 to 1 compression ratio and was actually approved to use 91 octane fuel