Compression ratios

[AC3000ME]

Hi all, not been on here for years as I went away from V8`s for a bit, but the calling has returned!

Hoping this has been done before, I am going to do a top end refresh on a 3.5L SD1 motor. I have some Thor heads that I will refurbish and do some very mild porting, keeping to standard valves, SU carbs, it has decent headers but will change to an uprated cam. At the moment it has the tin gaskets, if the Thor heads go on with tin gaskets, what will be the compression ratio? Raising it a bit will only help to get a bit more power. The Thor heads have never been skimmed. Looking to get 190 - 200bhp with strong mid range torque, the car only weighs 850kgs so I can trade off a bit of low down torque but would like it to pull to 5250 - 5500rpm without tailing off.

Dave