[Ramairnacho]

Happy holidays from Guadalajara, Mexico. Sometime next year I plan on having my engine gone through. It had sat for 25 years with zero miles on rebuilt engine. I have correct block yz Vin match. I have a fully restored set of #13 heads with harden seats ,new values springs but recently learned that I needed #12 to be correct , so I bought correct dated ones. The local machine shop in Concord,CA will be rebuilding engine and modernizing it inside. Adding roller cam and lifters. Gas octain is only 91 in California so builder wants dish pistons put in it. I believe I had a min. Bore of 0.20 th of inch to max block life. My factory compression ratio is 10.25 to 1 and builder want to bring it down to about 9 or 9.5 to 1. How much hp will I loose? Can I add 1.65 ratio roller rockers if so will it help? Some say it will run fine and leave it stock other say it will ping too much. I'm new at this so I'm hoping someone here has already modernized there engine,distributor and carb. Advise please