You'll be fine with 91 octane. The 575 is a well built, under tuned motor, with lots of room for build ups.
The stock compression ratio is only 7.5:1, and the stock blower setup makes 4PSI of boost.
I would change the head gaskets at the 1st opportunity. The stock head gaskets are the gray slick graphite GM stock type, which sucks. I'll bet 75% of the warranty claims Mercury had on these motors were due the stock gaskets blowing. Felpro makes a nice replacement version.
You might also want to check with Darren Mayer Performance Engineering for blower service. I've been very happy with them for sales and service. www.dmpeinc.com
Nice Gun, BTW!
Regards,
Steve

I've been watching that boat for a while, saw that it sold,
did the math, figured it was a good guess

I tried to talk myself in to it, but I knew
getting rid of the exsisting one now is
pretty much impossible..... I even turned
one of my friends on to it...but, he was in the same boat.

Looks like a sweet ride though, good luck with it.

Came from Florida, Lucky Strike Jr may have some history. I had traded e-mails with him about it before it came up to Missouri.

I was interested in it but came across Kevins boat which worked better for what I wanted to do. Looks like they were able to move a number of boats this fall.

Kevin has been a great source of advice on this whole process, and that Tiger he has is really sweet!!!
Hopefully we will have the trailer and take delivery right after Thanksgiving. So if you hear some noise that week on LOTO it SHOULD be me!!
Quinlan

Great looking cig. You'll like the 575's. I've used DMPE, talk to Bryan Dietz on the blower work. He'll hook you up.
Enjoy

Talked to the Blower shop today. Will be sending in this winter.Cheap ins for trouble free boating!!!! Now how to package them so UPS cant phuk them up.

Well now there is an issue w one motor. I guess the dist shaft and the cam had an issue working together! They are replacing the shaft, cam and lifters. Need some opinions on what might cause this?
Quinlan

I have heard of distributer issues but cant remember if it is soft metal on the dist or cam gear. May be a good time to upgrade cams and headgaskets on both motors.

If there is metal from the cam gear and distributor gear in the engine, then the entire engine should be gone through.