Thats really too bad with that situation. Most of the proper fixes cost more money, but things you can do is try to get a cam with more overlap which will bleed off pressure as techi said. Heads with more bigger chambers could help. I run about 10.7 or so on my 355 and I just use 91-93 and never detonate but that's also with the properly set up quench or 'squish'. You could deck the block for better quench but then still have to use bigger chambered heads to bring the CR down. This depends on how far down the pistons are just as Richard said. Cheapest fix is a bigger head and a cam with more overlap, but keep in mind the downsides of more overlap too.