Valve seats and octane level

[Paul Beijer +31 40 2736276 <Paul.Beijer@domain.elided>]

Hi all,

I own a '71 1310 with a 304 engine. The only way to run it on a daily basis
with Dutch gass-prices is converting to propane. I read somewhere that IH
offered an LPG factory option for the 304 as well as for the 345. Does this
mean that my valveseats are allready suitable for propane?
If I run it on gasoline, what octane level should I use? Compression ratio is
not that high (8.19:1), so I would expect that I can run it on regular.

Thanks,
Paul