You will need to watch you valve to piston clearance with a truly stock bottom end. I doubt a Hughes 6368 would clear without valve reliefs. It might,but it will be close.
Also the heads will need work to get that much lift before the retainer/ valve guide clearance becomes an issue.
400 hp naturally aspirated is do able. 450 is going to be hard to do because of the above.
Getting the cam right for the rpm range you will run it in,and decent heads are the important factors for a low compression deal to work. You would be better off trying to optimize midrange torque than going for high rpm power with a stock short block.
Keith