I'm planning to do some performance modifications when I rebuild its engine. Among those I have some ideas of which I'm not sure if they would be appropriate, so I'd like to hear some advice from the M30 experts

First, I'd like to increase compression a bit, first and foremost because the engine is tuned for 91 RON fuel, and the worst fuel I can get is RON 95, so I feel I'm losing some potential here. The other reason is that I'll be installing a performance camshaft, which lowers the dynamic compression even more, so I feel that the engine would make much better use of the camshaft and the fuel if the compression is increased.

I've researched methods for raising the compression and discussed it here before, and found what options are available. The best one would be to get custom pistons, but since they alone can be worth more than the whole engine, I think I'll skip that. The popular method of head shaving seems to inevitably leads to multiple head cracks, so it's also out, and I was also advised against using thinner gaskets with this engine.

So, the only viable option that remains is lowering the deck, which I believe shouldn't pose a problem considering the deck clearance, gasket thickness and valve lift at TDC; cam phasing also seems not to be much of a problem considering the amount of head lowering would be very small. I suppose my target would be something between 10-10.5 CR

A new idea that occured to me is to try using S38B38 crankshaft if I can find one, and if I can combine it properly with the rest of the M30 parts. That should increase the stroke from 86mm to 90mm, consequently lifting the piston at TDC by 2mm. I believe the piston still wouldn't interfere with anything then, that would rise compresion, but I'm not sure if it would be too much, by my estimate it would go up to 11. So, any ideas, opinions and warnings considering this combinations would be welcome.

The other question is, how much CR can M30 take anyway without detonating and without need for drastic ignition retard? The fuel used would be RON 95 and if necessary RON 98. For what I know, the chamber hasn't too bad a shape, and this M30 version has reasonably flat pistons, but perhaps the squish zones are too wide for good detonation-free combustion?

Besides compression, there is another small mod which is popular with some other engines, and I'm not sure how about M30 - valve machining. The options are three-angle job (which I believe could be beneficial), stem undercut and radiusing the backside. I don't know if M30's valves would benefit from those mods, and would it even be harmful for them?

Sorry I got this wordy, but I tried to explain in detail what I have in mind in hope someone would help me with similar experiences, or even to warn me which of those ideas would be idiotic to do

Thanks in advance!