340 Build Advice

Hello all, I’m seeking advice on a 340 build. I have no experience building engines need some guidance on matching parts and what all will be required for the build. Im going to try and locate an experienced builder to put it together but figured it would be nice to know what I should gather before that time comes. I’ve located 2 340 blocks, one a 73 and one a 69. Both have been machined .030 over. The car it’s going in will be used mostly for street driving and some auto cross and would like it to produce around 400-500 hp. Additional, it’ll most likely be using an efi system. If you’re knowledgable in this area let me know.

I think I would go 4.00” stroke crank and flat top pistons with tight quench.
As mentioned a 400 horsepower 340 is fairly easy but 500 the price goes up quite a bit along with the RPM range and the street ability heads the other direction. a little more manageable with a four-speed. A 500 horsepower 340 is awesome but it ain't cheap.