I'm gonna' build a new engine for my mustang and I'm looking at several different rebuild/stroker kits. I'm gonna build a 347 out of my 5.0 or a 408 out of my '94 351w roller block. I noticed that most of them steer you to the direction of 10.5:1 compression with 64cc combustion chamber heads, but if you specify a dish to the pistons it drops compression to 9.4:1 to 9.7:1ish depending on the size of the dish. I'm going to use the car as a weekend street machine I could care less about paying $2.00 more for a 20 gallon fill up to use 93 octane premium fuel...I'm worried that if I run 10.5:1 compression and the wife or someone else uses 87 octane regular it will suffer detonation. Will I loose significant HP & TQ by droping my compression? I'm looking to get 350ish HP out of a 347 or 425ish out of the 408 and either would live its life under 6,200 RPM...also I never plan on using a power adder should pay more and use forged slugs or would hyper's be fine in a 408 pushing a little over 400hp