I think it is unlikely that this would work, the 300hp engine is fitted with high compression cylinders so for that type of engine the answer is "NO".
If you are talking of the 240hp engine with the low compression cylinders then the answer is "maybe".
The thing to be remembered about Avgas 100LL is that it has an octaine rating of 130 with a rich mixture and 100 when leaned off, I dont think that at full power the 300hp IO540 would take kindly to a 98 octaine fuel.