Hardened Valve Seats?

[Wayne]

When rebuilding the heads for these sandy's is it necessary to have hardened valve seats installed? Here in Canada there no no such thing as leaded fuel and hasn't been for years. We have Unleaded only, as high as 94 Octane and up to 10% Ethanol. In my experience with older Automotive engines that had soft valve seats designed for leaded fuel we had to replace the seats or they would crack in no time. Thoughts?
 

[Wayne]

I think I found my answer but I'll leave the post anyway.

Found info that says if the head is made of aluminum then it will have hardened valve seats already installed. Only old cast cylinder heads had to have the seats updated for modern fuels.

If so, this is good!