Wobbly, in my previous career life, we used to bump up the compression on comp engines running at Denver to 17+:1 in order to make any power up there. If there is no air to begin with, you better compress it all you can.
The tough spot is that it is extremely hard to do with a small bore engine like you have. The best option is to start where you are, dyno the thing and move the cams where you want, then get a new piston blank with a blob dome and clearance it to barely fit and clear the valves now that they are in the right spots and make a new set of pistons off that. It is a major pain but that will do the trick.