500 vs 512 from 400ci

Just got of the phone with Bill Miller, wow what a source of information. It amazes me that you get these companies in USA, you call them and talk to the guy himself. Amazing!
He said I dont need a griddle because I'm not planning to make enough power to ever need it ;-)
His suggestion is to use aluminium main caps with studs. Offered a set of rods with pistons and rings for 3500$ which sounds tempting.
This will exceed my initial budget by over 1000$ with Molnar crankshaft but If this is going to make it possible, I'm in.